CHANGELOG.md

# Changelog

> **Tags:**
>
> - :boom: [Breaking Change]
> - :eyeglasses: [Spec Compliance]
> - :rocket: [New Feature]
> - :bug: [Bug Fix]
> - :memo: [Documentation]
> - :nail_care: [Polish]
> - :house: [Internal]

# 13.0.0-alpha.6 (Unreleased)

#### :boom: Breaking Change

- Reject malformed UTF-8 in documentation comments and invalid string or template literal escapes that were previously accepted, including empty or out-of-range braced Unicode escapes (`\u{}`, `\u{110000}`) and legacy decimal or octal escapes in templates (`\1`, `\01`, `\8`). These inputs now produce syntax diagnostics instead of compiling to invalid or inconsistent JavaScript. https://github.com/rescript-lang/rescript/pull/8606
- Reject tagged template literals in patterns. Patterns cannot invoke their tag; previously their raw payload was compiled as a plain string comparison. https://github.com/rescript-lang/rescript/pull/8606
- Remove runtime APIs that were deprecated for removal in ReScript 13, including the `Char` module, unsafe `Obj` operations, legacy `Pervasives` helpers, and `Array.unsafe_get`. https://github.com/rescript-lang/rescript/pull/8564
- Remove the deprecated `Js` namespace and its runtime modules. https://github.com/rescript-lang/rescript/pull/8531
- Move Belt into the separately installed `@rescript/belt` package. Projects using Belt must install the package and list it in their `rescript.json` dependencies. https://github.com/rescript-lang/rescript/pull/8554
- Correct the structured function details produced by `rescript-tools doc` and exposed by `RescriptTools.Docgen`: parameters now retain labels and optionality, nested functions, tuples, variables, and generic arguments retain their type structure, return types are identified correctly, and non-function values no longer receive fake function details. This changes the published docgen detail schema. https://github.com/rescript-lang/rescript/pull/8576
- Make object-field mutability part of the type. A property has one type for reading and writing. Assignment requires `@set`, except on an inferred open row, where assignment makes the field settable. Private rows are not inferred open rows, so a field in `type t = private {.."x": int}` is writable only when annotated with `@set`. Coercions never grant or widen write capability. Previously, getter and setter types were tracked independently, allowing a property to be written at a different type than it was read and allowing writes through a value coerced to a type without `@set`. https://github.com/rescript-lang/rescript/pull/8597
- Remove the undocumented object-field attribute forms `@get` (bare or with a `null`/`undefined`/`nullable` payload) and `@set({no_get: ...})` on object types. Only bare `@set` marks a field settable; nullable getter types are written directly (`null<t>`, `undefined<t>`, `nullable<t>`). https://github.com/rescript-lang/rescript/pull/8597

#### :eyeglasses: Spec Compliance

#### :rocket: New Feature

- Support UTF-16 surrogate-pair escapes such as `"\uD83D\uDE00"` in ordinary string literals. https://github.com/rescript-lang/rescript/pull/8606
- Support dynamic imports of external bindings annotated with `@scope`; the generated import follows the complete property path. These imports were previously rejected. https://github.com/rescript-lang/rescript/pull/8582
- Add `@res.hoistedFunction` for emitting nested module functions as flat JavaScript exports. https://github.com/rescript-lang/rescript/pull/8402
- Add source map support with linked, inline, and hidden modes. https://github.com/rescript-lang/rescript/pull/8393
- Add `List.includes`, deprecate `List.has` in favor of `List.some`, and clarify the equality semantics of `List.includes` and `Array.includes`. https://github.com/rescript-lang/rescript/pull/8530

#### :bug: Bug fix

- Fix excessive parentheses and indentation in function assignments to refs, align record and array assignment formatting across refs and fields, and preserve function return-type parentheses and consistent JSX fragment layout in callbacks. https://github.com/rescript-lang/rescript/pull/8611
- Fix a recursive module with an empty signature discarding its right-hand side. Lambda-to-Lam conversion rewrote `Pupdate_mod` to unit when the module's shape had no fields, dropping the primitive's arguments - one of which is the right-hand side - so `module rec M: {} = { let () = Console.log("effect") }` emitted nothing for `M`. The elision now happens where the bindings are produced, with the right-hand side still in hand. https://github.com/rescript-lang/rescript/pull/8608
- Fix `Int.Ref.increment` and `Int.Ref.decrement` evaluating their argument twice: `Int.Ref.increment(mkRef())` emitted `mkRef().contents = mkRef().contents + 1 | 0`. The `%incr` and `%decr` builtins lowered to an assignment that repeated the argument expression; they now bind the reference before the read-modify-write. Inlining decisions around an increment are taken on the code it stands for rather than on a single primitive node. https://github.com/rescript-lang/rescript/pull/8608
- Fix a compiler crash on a polymorphic variant whose numeric name exceeds the `int32` range. `#99999999999("a")` and the same name in a pattern failed with `Failure("Int32.of_string")` and no location, because the range check ran in the frontend AST pass and matched only payload-free expressions. It now runs in `Typecore`, next to the integer literal decoding whose overflow error it mirrors, and covers both label positions. A bare `type t = [#99999999999]` still compiles, since nothing decodes a row field name. https://github.com/rescript-lang/rescript/pull/8608
- Object typing errors now describe fields directly: assigning to a field without `@set` reports that the field is not settable and suggests the annotation, and missing-property errors name the field instead of a phantom `"x#="` member. https://github.com/rescript-lang/rescript/pull/8597
- Fix pattern matching for string literals with equivalent runtime values but different escape spellings, preserving source order and reporting redundant patterns. https://github.com/rescript-lang/rescript/pull/8606
- Fix signature inclusion rejecting equivalent object externals after type-alias expansion. https://github.com/rescript-lang/rescript/pull/8581
- Fix externals whose result type is an alias of `unit` so they use the same unit-return behavior as externals declared to return `unit`. https://github.com/rescript-lang/rescript/pull/8581
- Fix dynamic imports of external bindings that require FFI argument or result conversions, including `@variadic`, `@unwrap`, polymorphic variant encodings, `@as` phantom arguments, optional labeled arguments, and `@return` wrappers. The imported value now applies the same conversions as a direct external call. https://github.com/rescript-lang/rescript/pull/8582
- Fix formatter breaking the opening brace of a functor module type's result signature onto a new line (e.g. `module Make: Pattern => {`). https://github.com/rescript-lang/rescript/pull/8519
- Fix argument evaluation order when a function call is inlined: the beta reducer stacked argument bindings in reverse parameter order, so the last argument was evaluated first when arguments could not be substituted directly. https://github.com/rescript-lang/rescript/pull/8572
- Preserve parentheses around multiplication, division, and modulo expressions used as exponents. https://github.com/rescript-lang/rescript/pull/8550
- Make a function's locally abstract types (`(type t, x) => ...`) part of the function AST node instead of a chain of wrapper nodes. Fixes the formatter dropping the association of attributes with their `type` group (`(@attr type t, x, @attr2 type s, y)` used to print as `@attr @attr2` on the function) and comments written next to a type parameter migrating onto the following value parameter. https://github.com/rescript-lang/rescript/pull/8574
- Preserve trailing comments between the type and `=` in locally abstract value constraints (`let f: type a. t /* comment */ = value`). https://github.com/rescript-lang/rescript/pull/8575
- Enforce function arity in interface/module inclusion and type coercion. Previously a curried implementation (e.g. `int => int => int`) could satisfy an uncurried interface (`(int, int) => int`) or be coerced to it, which could miscompile calls made through the interface type. Such mismatches are now compile errors with an explanatory hint. https://github.com/rescript-lang/rescript/pull/8559
- Fix termination-analysis false positives for functions whose progress flows through un-annotated helpers: collecting the callees of a function binding was accidentally disabled in 2024 (the collection guard required a node shape that uncurried code never produces), so helpers calling `@progress` functions were no longer added to the function table. https://github.com/rescript-lang/rescript/pull/8568
- Fix default values of optional parameters being computed at the wrong time for curried functions: in `(~x=default, y) => (~z=default, w) => ...`, `x`'s default was only computed when the *inner* function was applied. Each default is now computed when its own parameter group is applied. https://github.com/rescript-lang/rescript/pull/8568
- Fix bare labeled arrow types (`~x: int => string`) getting no arity: they printed identically to their parenthesized form (`(~x: int) => string`) but did not unify with it. https://github.com/rescript-lang/rescript/pull/8563
- Fix losses of fidelity when code passes through an external PPX: the internal `@res.async` marker no longer leaks into the program, attributes on an arrow type or on an `await` expression are no longer dropped or relocated (previously this could crash the formatter), JSX elements keep their closing tag, and PPX-emitted OCaml-style `function` is desugared instead of crashing the compiler. https://github.com/rescript-lang/rescript/pull/8561
- Preserve multibyte characters when wrapping long source lines in compiler code frames. https://github.com/rescript-lang/rescript/pull/8520
- Fix reanalyze optional-argument diagnostics for functions passed or returned as first-class values. https://github.com/rescript-lang/rescript/pull/8321
- Prevent the developer playground from loading stale compiler and library assets after PR preview updates. https://github.com/rescript-lang/rescript/pull/8556

#### :memo: Documentation

#### :nail_care: Polish

- Print external declarations in signatures and type errors with their processed attributes instead of the `"#rescript-external"` placeholder, and print inline constants using `@inline` syntax. https://github.com/rescript-lang/rescript/pull/8581
- Improve diagnostics for dynamic imports of local values and attempts to use `import` as a first-class value. https://github.com/rescript-lang/rescript/pull/8582
- Allow inferred labeled functions to be called with labels in any order by removing legacy curried-arrow commutation locks. https://github.com/rescript-lang/rescript/pull/8547

#### :house: Internal

- Developer playground: Make panes resizable with wrapping text. https://github.com/rescript-lang/rescript/pull/8628
- Merge the duplicate Lam intermediate representation into Lambda, removing the conversion layer and obsolete supporting infrastructure. Lambda is now a single private, normalized representation, with generated JavaScript remaining semantically unchanged. https://github.com/rescript-lang/rescript/pull/8608
- Add genType and source map controls and output to the developer playground. https://github.com/rescript-lang/rescript/pull/8448
- Rework the object-type representation end to end: object rows are plain field chains carrying a per-field mutability state (no phantom setter members), object literals are typed directly and property access and assignment are first-class AST and Lambda nodes shared between the Lambda and JS pipelines, and dead class-system remnants (the field-presence lattice, the class-abbreviation memo on object types, method-send typing) are removed. https://github.com/rescript-lang/rescript/pull/8597
- Upgrade the development toolchain and primary CI builds to OCaml 5.5 while retaining OCaml 5.0 as the minimum supported version. https://github.com/rescript-lang/rescript/pull/8589
- Upgrade the vendored Flow parser from 0.267.0 to 0.320.0, the final release of the OCaml implementation. https://github.com/rescript-lang/rescript/pull/8588
- Vendor the Flow parser 0.267.0 sources used by the compiler, removing the external `flow_parser` dependency and establishing a maintained baseline for future OCaml upgrades. https://github.com/rescript-lang/rescript/pull/8587
- Store processed external declarations as structured data instead of serialized values in `pval_prim`, and lower external calls during Lambda translation. This removes `Pccall`, `external_spec`, and the unsupported `%absfloat` primitive. The AST, CMI, and CMT magic numbers are bumped (`ResImpl01301`/`ResIntf01301`, `Caml1999I025`, `Caml1999T026`). https://github.com/rescript-lang/rescript/pull/8581
- Resolve dynamic-import targets during Lambda translation and store the module and export path directly in `Pimport`. This removes the `dynamic_import` flags from `Pjs_call` and `Lglobal_module`, along with backend expression-shape detection. https://github.com/rescript-lang/rescript/pull/8582
- Give nominal variants one canonical runtime layout: compute their JavaScript representation once after typing each declaration, replace positional constructor tags with semantic runtime descriptors, and make construction, matching, coercion, printing, diagnostics, and GenType consume the stored representation instead of reinterpreting annotations. Pattern matching keeps occurrence-specific plans local without adding another Lambda or Lam expression form. https://github.com/rescript-lang/rescript/pull/8579
- Represent optional parameters with defaults structurally, removing downstream name-based detection and producing more consistent JavaScript parameter names. https://github.com/rescript-lang/rescript/pull/8580
- Sync the platform npm package's compiler binaries (`packages/@rescript/<platform>/bin`) via dune promotion on every `dune build`, instead of Makefile/CI copy steps that only ran when make did: a plain `dune build` can no longer leave `cli/*.js` and the test harnesses running a stale compiler. https://github.com/rescript-lang/rescript/pull/8560
- Remove unused compiler IR definitions, modules, helpers, error variants, and Typedtree fields. https://github.com/rescript-lang/rescript/pull/8551 https://github.com/rescript-lang/rescript/pull/8555
- Make Lambda-to-Lam conversion structural for lets, switches, static exits, recursive binding groups, exception packing, and eliminated identity operations. Semantic rewrites now happen during Lambda production or in named Lam passes; obsolete conversion state and `Lam_scc` are removed. https://github.com/rescript-lang/rescript/pull/8604
- Remove obsolete Lambda and Lam primitives and align their scalar constant representations. Lambda and Lam now use `int32` integers and matching char, string, float, and bigint cases; Lambda strings carry their parsed output delimiter, assert-false is distinct from integer zero, and dead typedtree integer variants are removed. https://github.com/rescript-lang/rescript/pull/8604
- Make locally abstract value constraints (`let f: type a. t = value`) structural in the parsetree, remove the obsolete `Pexp_newtype` and `Texp_newtype` wrapper metadata, and keep the old encoding confined to the frozen external-PPX bridge. The CMT magic number is bumped to `Caml1999T024`. https://github.com/rescript-lang/rescript/pull/8575
- Eliminate the `Pjs_fn_make`/`Pjs_fn_make_unit` arity-adjustment primitives and the `unsafe_adjust_to_arity` machinery: with structural arity, functions are constructed at their final arity, so the enforcement layer (and the active-pattern currying split it compensated for) is deleted. Generated code improves: no adapter closures for patterns on mutable fields, better constant propagation and name preservation, and recursive modules whose members are plain functions compile statically without the runtime bootstrap. https://github.com/rescript-lang/rescript/pull/8570
- Cleanups enabled by structural arity: remove the unreachable `Too_many_arguments` error and the `?in_function` threading through the type checker that existed only to decorate it; remove the dead `function$`-vs-arrow unification bridge, `Ctype.arity`, and the unused parsetree arity helpers; deduplicate the analysis arrow-flattening helpers. https://github.com/rescript-lang/rescript/pull/8569

- Make the typed layers n-ary as well: `Types.Tarrow` carries a parameter list, `Texp_function` carries typed parameters (label, ident, pattern, per-parameter exhaustiveness) and a body, and `Ttyp_arrow`/`Otyp_arrow` follow. The `arity` annotation and its `int option` phantom state are gone from the compiler entirely; `push_defaults` in translcore and the hand-rolled gather-until-arity walks in gentype, reanalyze, and the outcome printer are deleted. The cmi and cmt magic numbers are bumped (`Caml1999I023`/`Caml1999T023`). Generated JavaScript is byte-identical across the test suite (optional-parameter internals are named `*opt_<label>*` instead of `*opt*`, visible only in the rare unprettified case); reanalyze no longer emits spurious empty optional-argument references, and genType recovers real parameter names after defaulted parameters. https://github.com/rescript-lang/rescript/pull/8568
- Make functions and arrow types n-ary in the parsetree: `Pexp_fun` carries a parameter list and `Ptyp_arrow` a parameter list, replacing the curried one-parameter-per-node chains with an `arity` annotation on the head. Arity is now structural (`List.length params`) and `ast_uncurried.ml` is deleted. The typed layers, cmt format, printed output, and the external-PPX wire format are unchanged. Generated JavaScript is unchanged with one deliberate exception: `@this this => async arg => ...` now means what it says (a method returning an async function) instead of absorbing the nested parameter into the method; write `@this async (this, arg) => ...` for the old meaning. https://github.com/rescript-lang/rescript/pull/8566
- Give marshaled current-parsetree streams (`-as-pp`, `res_parser -print binary`) their own magic numbers, distinct from the frozen Parsetree0 wire format used for external PPXes. https://github.com/rescript-lang/rescript/pull/8561
- Record the written parameter count in parsed arrow arity for externals with phantom `@as(...) _` arguments. External processing recounts after erasing phantoms, so the parser no longer needs to pre-decrement the arity or the printer to compensate for it. https://github.com/rescript-lang/rescript/pull/8563
- Add the `-check-lam` compiler option, enable Lambda invariant checking in compiler tests, and remove build-profile-dependent checking. https://github.com/rescript-lang/rescript/pull/8534
- Replace `-bs-diagnose` with `-debug-ir` and make IR diagnostic artifacts deterministic, compilation-local, and easy to clean. https://github.com/rescript-lang/rescript/pull/8535
- Replace CPPO-based browser conditionals with Dune-selected native and playground compiler implementations. https://github.com/rescript-lang/rescript/pull/8541
- Replace compiler data-structure CPPO specializations with OCaml functors. https://github.com/rescript-lang/rescript/pull/8542
- Remove the obsolete CPPO generator for frozen Belt runtime specializations. https://github.com/rescript-lang/rescript/pull/8543

# 13.0.0-alpha.5

#### :boom: Breaking Change

- Make `Jsx.component` abstract. https://github.com/rescript-lang/rescript/pull/8390
- Drop Node.js version 20.x support, as it is reaching EOL. https://github.com/rescript-lang/rescript/pull/8401
- Remove the `@taggedTemplate` decorator in favor of the new first-class `taggedTemplate<'param, 'output>` builtin type. Using the decorator, or backtick tagged-template syntax on a value that is not a `taggedTemplate`, is now a compile error pointing to the new binding form. https://github.com/rescript-lang/rescript/pull/8461

#### :rocket: New Feature

- Add a first-class `taggedTemplate<'param, 'output>` builtin type and the `TaggedTemplate` stdlib module (`TaggedTemplate.make`). Tagged-template tags are now tracked through the type system, so they emit real JS tagged-template syntax across module boundaries, when passed as first-class values, and when constructed at runtime by a factory (e.g. `postgres`). https://github.com/rescript-lang/rescript/pull/8461
- Make mutation of private record mutable fields a configurable warning instead of a hard error. https://github.com/rescript-lang/rescript/pull/8366
- Add support for pattern matching/destructuring of record rest. https://github.com/rescript-lang/rescript/pull/8317

#### :bug: Bug fix

- Fix directive `@warning("-102")` not working. https://github.com/rescript-lang/rescript/pull/8322
- Fix duplicated comments in `for`..`of` formatter. https://github.com/rescript-lang/rescript/pull/8395
- Fix issue where warning 56 would blow up with `dict{}` patterns. https://github.com/rescript-lang/rescript/pull/8403
- Rewatch build lock fixes. https://github.com/rescript-lang/rescript/pull/8409 https://github.com/rescript-lang/rescript/pull/8410 https://github.com/rescript-lang/rescript/pull/8413 https://github.com/rescript-lang/rescript/pull/8424
- Rewatch: treat transitive workspace dependencies as local packages in monorepo roots. https://github.com/rescript-lang/rescript/pull/8411
- Rewatch: use a single timestamp per compile pass. https://github.com/rescript-lang/rescript/pull/8428
- Fix rewatch warning replay after early compile errors. https://github.com/rescript-lang/rescript/pull/8408
- Fix formatting of trailing comments before `=` in let bindings. https://github.com/rescript-lang/rescript/pull/8444
- Fix analysis namespace parsing after the Yojson migration. https://github.com/rescript-lang/rescript/pull/8454
- Fix namespaced reference lookup in editor analysis. https://github.com/rescript-lang/rescript/pull/8455
- Fix analysis segmentation fault for references after https://github.com/rescript-lang/rescript/pull/7887. https://github.com/rescript-lang/rescript/pull/8477
- Fix build crash when the compiler emits output that is not valid UTF-8, such as a truncated multibyte character in a code frame. https://github.com/rescript-lang/rescript/pull/8482
- Fix unnecessary boxing of `Some(React.component)`. https://github.com/rescript-lang/rescript/pull/8500
- Fix GenType React element output to support React 19 typedefs. https://github.com/rescript-lang/rescript/pull/8501

#### :nail_care: Polish

- Consolidate record mutation output into a single spread object literal. https://github.com/rescript-lang/rescript/pull/8473
- Improve default argument type mismatch errors. https://github.com/rescript-lang/rescript/pull/8389
- Resolve workspace dependencies in editor analysis. https://github.com/rescript-lang/rescript/pull/8392
- Build system: Add OpenTelemetry tracing support for cli commands. https://github.com/rescript-lang/rescript/pull/8370
- Use a single vendored @rescript/react package across the repo. https://github.com/rescript-lang/rescript/pull/7525
- Improve deprecated attribute extraction and support record form. https://github.com/rescript-lang/rescript/pull/8396
- Refactor analysis to decouple I/O from core logic. https://github.com/rescript-lang/rescript/pull/8426
- Deprecate `Stdlib_Error` and `Stdlib_Exn` modules in favor of `JsError/JsExn`. https://github.com/rescript-lang/rescript/pull/8404
- Remove vendored `Json` library and use `yojson` and `lsp` library for analysis. https://github.com/rescript-lang/rescript/pull/8436
- Improve clarity of various error and warning messages. https://github.com/rescript-lang/rescript/pull/8460

#### :house: Internal

- Remove `Primitive_option.toUndefined`; use `valFromOption` for optional ffi args. https://github.com/rescript-lang/rescript/pull/8380
- Add a developer playground for testing the current compiler bundle locally and deploy the latest `master` build to GitHub Pages. https://github.com/rescript-lang/rescript/pull/8435
- Expand `super_errors` fixture coverage for warnings and errors. https://github.com/rescript-lang/rescript/pull/8429
- Run `super_errors` fixtures in parallel (~2.4× faster locally). https://github.com/rescript-lang/rescript/pull/8430
- Expand `super_errors` fixture coverage for the remaining reachable single-file error variants. https://github.com/rescript-lang/rescript/pull/8432
- Cache OPAM env, rewatch build, and instrumented dune state in the coverage workflow. https://github.com/rescript-lang/rescript/pull/8434
- Add a multi-file fixture harness (`super_errors_multi`) for cross-module errors and warnings. https://github.com/rescript-lang/rescript/pull/8433
- Catalog every named compiler error variant in `tests/ERROR_VARIANTS.md` and add fixtures for the remaining reachable ones. https://github.com/rescript-lang/rescript/pull/8446
- Remove dead and unreachable compiler error and warning variants; add fixtures for the ones found to be reachable. https://github.com/rescript-lang/rescript/pull/8459
- Convert OCaml codebase to snake case format. https://github.com/rescript-lang/rescript/pull/8456
- Analysis refactor: remove global state `Shared_types.state`. https://github.com/rescript-lang/rescript/pull/8465
- Refactor analysis CLI helpers to use source input. https://github.com/rescript-lang/rescript/pull/8466
- Include syntax, gentype, analysis, tools, and reanalyze tests in coverage reports. https://github.com/rescript-lang/rescript/pull/8467
- Remove the unreachable `Longident.Lapply` constructor (OCaml's applicative-functor path syntax `F(X).t`, which ReScript's grammar cannot produce). https://github.com/rescript-lang/rescript/pull/8469
- Refactor analysis for server side use. https://github.com/rescript-lang/rescript/pull/8478
- Remove unused files. https://github.com/rescript-lang/rescript/pull/8481
- Remove the dead `Sig_class`/`Sig_class_type` signature variants (OCaml class items, which ReScript cannot produce). https://github.com/rescript-lang/rescript/pull/8470

# 13.0.0-alpha.4

#### :boom: Breaking Change

- Support for `break` and `continue` in loops. `break` and `continue` are new keywords. https://github.com/rescript-lang/rescript/pull/8348
- Fix iterator / iterable typedefs, add generator typedefs. https://github.com/rescript-lang/rescript/pull/8355
- Remove deprecated `%external` extension. https://github.com/rescript-lang/rescript/pull/8376
- Remove Belt API functions returning `undefined<'a>` (e.g., `Belt.Array.getUndefined`). Functions returning `option<'a>` should be used instead (e.g., `Belt.Array.get`). https://github.com/rescript-lang/rescript/pull/8377

#### :rocket: New Feature

- Implement `for...of` and `for await...of` loops. https://github.com/rescript-lang/rescript/pull/7887
- Add support for dict spreads: `dict{...foo, "bar": 2, ...qux}`. https://github.com/rescript-lang/rescript/pull/8369
- Rewatch: add `--prod` flag to `build`, `watch`, and `clean` to skip dev-dependencies and dev sources (`"type": "dev"`), enabling builds in environments where dev packages aren't installed (e.g. after `pnpm install --prod`). https://github.com/rescript-lang/rescript/pull/8347
- Rewatch: feature-gated source directories. Tag a source entry with `"feature": "<name>"` and select with `--features a,b` (or per-dep in `dependencies` / `dev-dependencies`) to include optional slices of a package's source tree at build time. Top-level `features` map supports transitive implications. https://github.com/rescript-lang/rescript/pull/8379
- Rewatch: improve watch output and add `--clear-screen` option. https://github.com/rescript-lang/rescript/pull/8373
- Add `Dict.assignMany`, `Dict.concat`, `Dict.concatMany`, `Dict.concatAll`, `Array.concatAll` to the stdlib. https://github.com/rescript-lang/rescript/pull/8364

#### :bug: Bug fix

- Fix partial application generalization for `...`. https://github.com/rescript-lang/rescript/pull/8343
- Rewatch: preserve warnings after atomic-save full rebuilds. https://github.com/rescript-lang/rescript/pull/8358
- Preserve JSX prop locations across the AST0 translation layer, fixing `0:0` editor diagnostics in PPX-related flows. https://github.com/rescript-lang/rescript/pull/8350
- Fix type lowering for `dict{}` and `async`, so you don't need to annotate one extra time when the type is known. https://github.com/rescript-lang/rescript/pull/8359
- Rewatch: don't suppress progress messages under `-v`/`-vv`. https://github.com/rescript-lang/rescript/pull/8371
- Rewatch: print 'Finished compilation' in watch plain output mode. https://github.com/rescript-lang/rescript/pull/8372

#### :nail_care: Polish

- Allow builds while watchers are running. https://github.com/rescript-lang/rescript/pull/8349
- Rewatch: restore backward compatibility for `bsconfig.json`. https://github.com/rescript-lang/rescript/pull/8368
- Restore parsing of the legacy `(. ...)` uncurried syntax for backwards compatibility with libraries still on older ReScript versions; emit a deprecation warning when it is used. Rewatch also surfaces this specific deprecation when it originates from an external dependency so users can report breakage upstream. https://github.com/rescript-lang/rescript/pull/8383
- Rewatch: replace wave-based compile scheduler with a work-stealing DAG dispatcher ordered by critical-path priority, avoiding the per-wave stall on the slowest file. https://github.com/rescript-lang/rescript/pull/8374

#### :house: Internal

- Move `rescript.json` reading out of `bsc` into rewatch; remove the custom OCaml JSON parser. https://github.com/rescript-lang/rescript/pull/8365

# 13.0.0-alpha.3

#### :boom: Breaking Change

- Change `Intl.Collator.compare` return type from `int` to `Ordering.t` (`float`). https://github.com/rescript-lang/rescript/pull/8289

#### :rocket: New Feature

- Reanalyze: add glob pattern support for suppress/unsuppress configurations (e.g., `"src/generated/**"`). https://github.com/rescript-lang/rescript/pull/8277
- Add optional `~locales` and `~options` parameters to `String.localeCompare`. https://github.com/rescript-lang/rescript/pull/8287
- Support inline records in external definitions. https://github.com/rescript-lang/rescript/pull/8304

#### :bug: Bug fix

- Reanalyze server: invalidate cache and recompute results when config changes in `rescript.json`. https://github.com/rescript-lang/rescript/pull/8262
- Fix `null` and array values incorrectly matching the `Object` branch when pattern matching on `JSON.t` (or other untagged variants with an `Object` case) in statement position. https://github.com/rescript-lang/rescript/pull/8279
- Fix rewatch panic when `package.json` has no `name` field. https://github.com/rescript-lang/rescript/pull/8291
- Fix unpacking first-class module in default argument of React component. https://github.com/rescript-lang/rescript/pull/8296
- Fix exception record field regression. https://github.com/rescript-lang/rescript/pull/8319
- Rewatch: ignore stale lock for unrelated process name. https://github.com/rescript-lang/rescript/pull/8316
- Fix handling of exotic identifiers for let bindings in GenType. https://github.com/rescript-lang/rescript/pull/8315

#### :nail_care: Polish

- Improve error message for dependency without `rescript.json`. https://github.com/rescript-lang/rescript/pull/8292

#### :house: Internal

- Reanalyze server: redesign incremental fixpoint with delete-then-rederive strategy and predecessor tracking, improving speed on deletions. https://github.com/rescript-lang/rescript/pull/8276
- Fix build tests failing silently. https://github.com/rescript-lang/rescript/pull/8295

# 13.0.0-alpha.2

#### :bug: Bug fix

- Fix compiler crash (`Fatal error: Parmatch.all_record_args`) when matching empty dict/record patterns. https://github.com/rescript-lang/rescript/pull/8246
- Fix `null` falling into the object branch instead of the wildcard when pattern matching on untagged variants with both `Object` and `null` cases. https://github.com/rescript-lang/rescript/pull/8253

#### :nail_care: Polish

- Build system: Watch only source folders from build state instead of the entire project directory, and report missing configured source folders. https://github.com/rescript-lang/rescript/pull/8219

#### :house: Internal

- Speed up dev container test by installing OCaml in docker image instead of in `postCreate.sh`. https://github.com/rescript-lang/rescript/pull/8230

# 13.0.0-alpha.1

#### :boom: Breaking Change

- Remove the legacy build system. Going forward, only the modern build system is supported, and the `rescript-legacy` command is not available anymore. https://github.com/rescript-lang/rescript/pull/8186 https://github.com/rescript-lang/rescript/pull/8212
- Remove support for `bsconfig.json`. https://github.com/rescript-lang/rescript/pull/8187
- `Int.fromString` and `Float.fromString` use stricter number parsing and no longer use an explicit radix argument, but instead support parsing hexadecimal, binary and exponential notation. https://github.com/rescript-lang/rescript/pull/8129
- Remove the deprecated module system names `es6` and `es6-global` (superseded by `esmodule`). https://github.com/rescript-lang/rescript/pull/8205
- Default to module system `esmodule`. https://github.com/rescript-lang/rescript/pull/8213
- Remove `external-stdlib` configuration option from `rescript.json`. This option was rarely used and is no longer supported. https://github.com/rescript-lang/rescript/pull/8175
- Remove the deprecated uncurried `(. args) => ...` function syntax. https://github.com/rescript-lang/rescript/pull/8211
- `js-post-build` now passes the correct output file path based on `in-source` configuration: when `in-source: true`, the path next to the source file is passed; when `in-source: false`, the path in the `lib/<module>/` directory is passed. Additionally, stdout and stderr from the post-build command are now logged. https://github.com/rescript-lang/rescript/pull/8190
- `js-post-build` command now runs in the directory containing the `rescript.json` where it is defined, instead of the unpredictable build invocation directory. This provides consistent behavior in monorepos. https://github.com/rescript-lang/rescript/pull/8195
- Remove support for deprecated `bs-dependencies`, `bs-dev-dependencies`, and `bsc-flags` configuration options. Use `dependencies`, `dev-dependencies`, and `compiler-flags` instead. https://github.com/rescript-lang/rescript/pull/8196
- `bsc`: remove legacy `-uncurried` flag. https://github.com/rescript-lang/rescript/pull/8201
- Remove deprecated cli flags `--dev`, `--create-sourcedirs` and `build -w`. https://github.com/rescript-lang/rescript/pull/8202
- Do not allow two different package specs with the same suffix to avoid conflicts. https://github.com/rescript-lang/rescript/pull/8214

#### :rocket: New Feature

- Reanalyze: add scoped `@@live`/`@@dead` annotations for marking module/file sections as live or dead. https://github.com/rescript-lang/rescript/pull/8197
- Stdlib: Added Array.zip, Array.unzip, Array.zipBy, and Array.partition. https://github.com/rescript-lang/rescript/pull/8244

#### :bug: Bug fix

- Reanalyze: fix reactive/server stale results when cross-file references change without changing dead declarations (non-transitive mode). https://github.com/rescript-lang/rescript/pull/8173
- Reanalyze: link record/variant label liveness across type re-exports (`type y = x = {...}`). https://github.com/rescript-lang/rescript/pull/8217
- Add duplicate package detection to rewatch. https://github.com/rescript-lang/rescript/pull/8180
- Rewatch: do not warn about "reanalyze" config field. https://github.com/rescript-lang/rescript/pull/8181
- Fix error when importing CommonJS runtime modules with `require()`. https://github.com/rescript-lang/rescript/pull/8194
- Rewatch: fix warnings from non-recompiled modules being lost during incremental builds in watch mode. https://github.com/rescript-lang/rescript/pull/8216

#### :nail_care: Polish

- Formatter no longer writes files when contents are already correctly formatted. https://github.com/rescript-lang/rescript/pull/8209
- Build system: Only log verbose "Generating AST for module" when actually parsing. https://github.com/rescript-lang/rescript/pull/8210

# 12.1.0

#### :rocket: New Feature

- Add support for `Set`, `Map`, `WeakSet` and `WeakMap` to `@unboxed`. https://github.com/rescript-lang/rescript/pull/8009
- Reanalyze: add reactive incremental analysis (`-reactive`, `-runs`, `-churn`) and Mermaid pipeline dumping (`-mermaid`). https://github.com/rescript-lang/rescript/pull/8092
- Reanalyze: add `reanalyze-server` (long-lived server) with transparent delegation for `rescript-tools reanalyze -json`. https://github.com/rescript-lang/rescript/pull/8127
- Add support of `js-post-build` in Rewatch. Note that `${file}` is now an absolute path. https://github.com/rescript-lang/rescript/pull/8151

#### :bug: Bug fix

- Fix rewatch swallowing parse warnings (e.g., for `%todo`). https://github.com/rescript-lang/rescript/pull/8135
- Rewatch: log errors and warnings to `stderr`. https://github.com/rescript-lang/rescript/pull/8147 https://github.com/rescript-lang/rescript/pull/8148
- Rewatch: warn about deprecated package specs `es6`/`es6-global`. https://github.com/rescript-lang/rescript/pull/8146
- Fix formatter removing doc comments for polymorphic variants. https://github.com/rescript-lang/rescript/pull/8155

#### :nail_care: Polish

- Rewatch: enable `--create-sourcedirs` by default (now deprecated when explicitly used). https://github.com/rescript-lang/rescript/pull/8092
- Rewatch: check if filename case for interface and implementation matches. https://github.com/rescript-lang/rescript/pull/8144

# 12.0.2

#### :rocket: New Feature

#### :bug: Bug fix

- Reanalyze: make optional args analysis liveness-aware, preventing false positives when functions are only called from dead code. https://github.com/rescript-lang/rescript/pull/8082
- Fix: do not warn for "editor" field in `rescript.json`. https://github.com/rescript-lang/rescript/pull/8084
- Fix `@val` shadowing (rewrite using `globalThis`). https://github.com/rescript-lang/rescript/pull/8098
- Fix `@scope` shadowing (rewrite using `globalThis`). https://github.com/rescript-lang/rescript/pull/8100
- Formatter: normalize underscore placeholders in pipe expressions to canonical form (e.g., `a->map2(_, fn)` formats to `a->map2(fn)`). https://github.com/rescript-lang/rescript/pull/8033
- Fix rewatch panic on duplicate module name. https://github.com/rescript-lang/rescript/pull/8102
- Fix `let?` unwrap to use actual variable names from pattern instead of hardcoded "x"/"e". https://github.com/rescript-lang/rescript/issues/8085
- Fix "Ill-formed list of warnings" errors for PPXs with rescript-legacy. https://github.com/rescript-lang/rescript/pull/8103
- Fix gentype generating invalid syntax for exotic / escaped record field names and type names. https://github.com/rescript-lang/rescript/pull/8087

- Formatter: Improve multiline printing of record types and values. https://github.com/rescript-lang/rescript/pull/7993

#### :house: Internal

- Reanalyze: refactor DCE to pure pipeline architecture for order-independence and incremental update support. https://github.com/rescript-lang/rescript/pull/8043

# 12.0.1

#### :bug: Bug fix

- Fix exponential compilation blowup with large unboxed variants and dict pattern matching. https://github.com/rescript-lang/rescript/pull/8078
- Rewatch: warnings for unsupported/unknown `rescript.json` fields. https://github.com/rescript-lang/rescript/pull/8031
- Fix missing `ignore` function in some Stdlib modules. https://github.com/rescript-lang/rescript/pull/8060
- Fix signature matching for externals when abstract alias hides function arity. https://github.com/rescript-lang/rescript/pull/8045
- Fix arity detection for arrows returning nested generics. https://github.com/rescript-lang/rescript/pull/8064
- Fix error handling when `rescript.json` parsing fails and improve error message. https://github.com/rescript-lang/rescript/pull/8067
- Fix invalid JSX being generated for empty fragments. https://github.com/rescript-lang/rescript/pull/8077

#### :nail_care: Polish

- Add missing deprecation and migration for `Exn.Error`. https://github.com/rescript-lang/rescript/pull/8036

# 12.0.0

No changes compared to rc.5.

# 12.0.0-rc.5

#### :bug: Bug fix

- Fix printing of tagged template literals. https://github.com/rescript-lang/rescript/pull/8018
- Fix printing of optional record fields in pattern matching errors. https://github.com/rescript-lang/rescript/pull/8019

#### :house: Internal

- Editor: resolve `@rescript/runtime` via environment variable `RESCRIPT_RUNTIME`. https://github.com/rescript-lang/rescript/pull/8023
- Remove leftovers from `@meth` attribute. https://github.com/rescript-lang/rescript/pull/8022

# 12.0.0-rc.4

#### :boom: Breaking Change

- Fix some `Intl` bindings (`Intl.Collator.supportedLocalesOf`, `Intl.DateTimeFormat.supportedLocalesOf`, `Intl.ListFormat.supportedLocalesOf`, `Intl.NumberFormat.supportedLocalesOf`, `Intl.PluralRules.supportedLocalesOf`, `Intl.RelativeTimeFormat.supportedLocalesOf`, `Intl.Segmenter.supportedLocalesOf`) which return `array<string>` and not their corresponding main type `t`. Also remove `Intl.PluralRules.selectBigInt` and `Intl.PluralRules.selectRangeBigInt` which don't work in many JS runtimes. https://github.com/rescript-lang/rescript/pull/7995

#### :bug: Bug fix

- Fix fatal compiler error that occurred when an `%ffi` extension point contained invalid JavaScript. https://github.com/rescript-lang/rescript/pull/7998

#### :nail_care: Polish

- Dedicated error messages for old Reason array literal syntax (`[|` and `|]`), and for the old pipe (`|>`). Primarly intended to help LLMs that might try to use old code patterns. https://github.com/rescript-lang/rescript/pull/8010

#### :house: Internal

- Rename `Core` to `Stdlib` in tests/tests. https://github.com/rescript-lang/rescript/pull/8005
- CI: Build on `windows-2025` runners. https://github.com/rescript-lang/rescript/pull/8006
- Rewatch: upgrade Rust to 1.91.0. https://github.com/rescript-lang/rescript/pull/8007

# 12.0.0-rc.3

#### :bug: Bug fix

- Fix @directive on function level with async and multiple parameters. https://github.com/rescript-lang/rescript/pull/7977
- Fix fatal error for external with @as. https://github.com/rescript-lang/rescript/pull/7978

#### :nail_care: Polish

- Rewatch: plain output when not running in tty. https://github.com/rescript-lang/rescript/pull/7970
- Streamline rewatch help texts. https://github.com/rescript-lang/rescript/pull/7973
- Rewatch: Reduced build progress output from 7 steps to 3 for cleaner, less verbose logging. https://github.com/rescript-lang/rescript/pull/7971

#### :house: Internal

- Clean up usage of `Ast_uncurried` helpers. https://github.com/rescript-lang/rescript/pull/7987

# 12.0.0-rc.2

#### :boom: Breaking Change

- Replace binary operators with F#-style `~~~`, `^^^`, `&&&`, `|||`. https://github.com/rescript-lang/rescript/pull/7894

#### :bug: Bug fix

- Fix: use configured Jsx module for constraining component return type. https://github.com/rescript-lang/rescript/pull/7945
- Undeprecate `Js_OO` module since it is still used with the `@this` attribute. https://github.com/rescript-lang/rescript/pull/7955
- Fix crash when using bitwise not (`~~~`) on an incompatible type. https://github.com/rescript-lang/rescript/pull/7965

#### :house: Internal

- JSX PPX: use `React.component` instead of `React.componentLike` for externals. https://github.com/rescript-lang/rescript/pull/7952

# 12.0.0-rc.1

#### :nail_care: Polish

- Improve circular dependency errors, and make sure they end up in the compiler log so the editor tooling can surface them. https://github.com/rescript-lang/rescript/pull/7940
- JSX PPX: add Jsx.element return constraint. https://github.com/rescript-lang/rescript/pull/7939

#### :house: Internal

- Use AST nodes with locations for fn arguments in the typed tree. https://github.com/rescript-lang/rescript/pull/7873

# 12.0.0-beta.14

#### :boom: Breaking Change

- Removed `rescript legacy` subcommand in favor of separate `rescript-legacy` binary. https://github.com/rescript-lang/rescript/pull/7928
- Add comparison function for `Error` in `Result.equal` and `compare`. https://github.com/rescript-lang/rescript/pull/7933
- Rewatch: `"type": "dev"` and `dev-dependencies` will be compiled by default for local packages. The `--dev` flag no longer does anything. https://github.com/rescript-lang/rescript/pull/7934

#### :bug: Bug fix

- Prevent lockfile creation when project folder is missing. https://github.com/rescript-lang/rescript/pull/7927
- Fix parameter type / return type ambiguity error for unit case. https://github.com/rescript-lang/rescript/pull/7930

#### :nail_care: Polish

- ReScript cli: do not show build command options in the root help. https://github.com/rescript-lang/rescript/pull/7715
- Deprecate reanalyze `@raises` in favor of `@throws`. https://github.com/rescript-lang/rescript/pull/7932

#### :house: Internal

- CI: run macOS builds on macOS 15. https://github.com/rescript-lang/rescript/pull/7935

# 12.0.0-beta.13

#### :bug: Bug fix

- Fix result examples. https://github.com/rescript-lang/rescript/pull/7914
- Make inline record fields that overlap with a variant's tag a compile error. https://github.com/rescript-lang/rescript/pull/7875

#### :nail_care: Polish

- Keep track of compiler info during build. https://github.com/rescript-lang/rescript/pull/7889
- Improve option optimization for constants. https://github.com/rescript-lang/rescript/pull/7913
- Option optimization: do not create redundant local vars. https://github.com/rescript-lang/rescript/pull/7915
- Js output: remove superfluous newline after every `if`. https://github.com/rescript-lang/rescript/pull/7920
- Rewatch: Traverse upwards for package resolution in single context projects. https://github.com/rescript-lang/rescript/pull/7896
- Rewatch: Add `--warn-error` flag to `build`. https://github.com/rescript-lang/rescript/pull/7916

# 12.0.0-beta.12

#### :boom: Breaking Change

- Make experimental-features kebap-case in compiler config like the other fields. https://github.com/rescript-lang/rescript/pull/7891

#### :rocket: New Feature

- Add `littleEndian` feature for `DataView` to Stdlib. https://github.com/rescript-lang/rescript/pull/7881
- Add `mapOkAsync`, `mapErrorAsync`, `flatMapOkAsync` and `flatMapErrorAsync` for async `result`s to Stdlib. https://github.com/rescript-lang/rescript/pull/7906

#### :bug: Bug fix

- Include `-runtime-path` as bsc argument when generating `.mlmap` file. https://github.com/rescript-lang/rescript/pull/7888

#### :nail_care: Polish

- Add (dev-)dependencies to build schema. https://github.com/rescript-lang/rescript/pull/7892
- Dedicated error for dict literal spreads. https://github.com/rescript-lang/rescript/pull/7901
- Dedicated error message for when mixing up `:` and `=` in various positions. https://github.com/rescript-lang/rescript/pull/7900

# 12.0.0-beta.11

#### :boom: Breaking Change

- Have `String.charCodeAt` return `option<int>`; add `String.charCodeAtUnsafe`. https://github.com/rescript-lang/rescript/pull/7877
- Remove support of JSX children spread. https://github.com/rescript-lang/rescript/pull/7869

#### :rocket: New Feature

- Add `Array.filterMapWithIndex` to Stdlib. https://github.com/rescript-lang/rescript/pull/7876

#### :bug: Bug fix

- Fix code generation for emojis in polyvars and labels. https://github.com/rescript-lang/rescript/pull/7853
- Add `reset` to `experimental_features` to correctly reset playground. https://github.com/rescript-lang/rescript/pull/7868
- Fix crash with `@get` on external of type `unit => 'a`. https://github.com/rescript-lang/rescript/pull/7866
- Fix record type spreads in inline records. https://github.com/rescript-lang/rescript/pull/7859

#### :nail_care: Polish

- Reactivate optimization for length of array literals. https://github.com/rescript-lang/rescript/pull/7872
- `Float.isNaN`: use `Number.isNaN` instead of global `isNaN`. https://github.com/rescript-lang/rescript/pull/7874

#### :house: Internal

- Playground: Add config options for experimental features and jsx preserve mode. https://github.com/rescript-lang/rescript/pull/7865
- Clean up tests. https://github.com/rescript-lang/rescript/pull/7861 https://github.com/rescript-lang/rescript/pull/7871
- Add `-runtime-path` flag to `bsc` (and `bsb`), we are detecting the location of `@rescript/runtime` in `cli/rescript.js` based on runtime module resolution. https://github.com/rescript-lang/rescript/pull/7858

# 12.0.0-beta.10

#### :rocket: New Feature

- Support mapping more standard library types automatically to TS types via `gentype`, without requiring shims. https://github.com/rescript-lang/rescript/pull/7842

#### :bug: Bug fix

- Show `Stdlib.TypedArray` completions for typed arrays. https://github.com/rescript-lang/rescript/pull/7827
- Show `Stdlib.Null` and `Stdlib.Nullable` completions for `Stdlib.null<'a>` and `Stdlib.nullable<'a>` types, respectively. https://github.com/rescript-lang/rescript/pull/7826
- Fix generation of interfaces for module types containing multiple type constraints. https://github.com/rescript-lang/rescript/pull/7825
- JSX preserve mode: fix "make is not a valid component name". https://github.com/rescript-lang/rescript/pull/7831
- Rewatch: include parser arguments of experimental features. https://github.com/rescript-lang/rescript/pull/7836
- Stop mangling tagged templates and backquoted strings. https://github.com/rescript-lang/rescript/pull/7841
- JSX v4: fix arity mismatch for `@react.component` with `React.forwardRef`. https://github.com/rescript-lang/rescript/pull/7845

#### :nail_care: Polish

- Improve error message for trying to define a type inside a function. https://github.com/rescript-lang/rescript/pull/7843
- Refactor CLI to use spawn for better signal handling in watch mode. https://github.com/rescript-lang/rescript/pull/7844

- Add a `prepareRename` command the LSP can use for faster renames. https://github.com/rescript-lang/rescript/pull/7847

# 12.0.0-beta.9

#### :boom: Breaking Change

- Extract ReScript runtime files from main `rescript` package to separate `@rescript/runtime` package. https://github.com/rescript-lang/rescript/pull/7796
- Remove `@rescript/std` (in favor of `@rescript/runtime`). https://github.com/rescript-lang/rescript/pull/7811

#### :rocket: New Feature

- Add support for `ArrayBuffer` and typed arrays to `@unboxed`. https://github.com/rescript-lang/rescript/pull/7788
- Experimental: Add `let?` syntax for unwrapping and propagating errors/none as early returns for option/result types. https://github.com/rescript-lang/rescript/pull/7582
- Add support for shipping features as experimental, including configuring what experimental features are enabled in `rescript.json`. https://github.com/rescript-lang/rescript/pull/7582

#### :bug: Bug fix

- Fix JS regex literal parsing in character classes. https://github.com/rescript-lang/rescript/pull/7790
- Fix creating interface for functions with upper bounded polymorphic args. https://github.com/rescript-lang/rescript/pull/7786

#### :nail_care: Polish

- Make parser less strict around leading attributes. https://github.com/rescript-lang/rescript/pull/7787
- Dedicated error message for ternary type mismatch. https://github.com/rescript-lang/rescript/pull/7804
- Dedicated error message for passing a braced ident to something expected to be a record. https://github.com/rescript-lang/rescript/pull/7806
- Hint about partial application when missing required argument in function call. https://github.com/rescript-lang/rescript/pull/7807
- More autocomplete improvements involving modules and module types. https://github.com/rescript-lang/rescript/pull/7795
- Autocomplete `@react.componentWithProps` attribute. https://github.com/rescript-lang/rescript/pull/7812
- Add some missing iframe attributes to `domProps`. https://github.com/rescript-lang/rescript/pull/7813
- Polish error message for inline record escaping scope. https://github.com/rescript-lang/rescript/pull/7808
- Formatter: Change placement of closing `>` in JSX. https://github.com/rescript-lang/rescript/pull/7803

#### :house: Internal

- Build runtime with rewatch on Windows, too. https://github.com/rescript-lang/rescript/pull/7794

# 12.0.0-beta.8

Do not use, npm package broken.

# 12.0.0-beta.7

#### :rocket: New Feature

- Add markdown divider between module doc and module type in hover information. https://github.com/rescript-lang/rescript/pull/7775
- Show docstrings before type expansions on hover. https://github.com/rescript-lang/rescript/pull/7774
- Autocomplete (and improved hovers) for first-class module unpacks. https://github.com/rescript-lang/rescript/pull/7780

#### :bug: Bug fix

- Fix semantic highlighting for array spreads, array access and dict literals. https://github.com/rescript-lang/rescript/pull/7789
- Preserve `@as(...)` decorator on record fields when creating interface. https://github.com/rescript-lang/rescript/pull/7779
- Fix parse error with nested record types and attributes on the field name that has the nested record type. https://github.com/rescript-lang/rescript/pull/7781
- Fix ppx resolution with package inside monorepo. https://github.com/rescript-lang/rescript/pull/7776
- Fix 'Unbound module type' errors that occurred when trying to async import modules. https://github.com/rescript-lang/rescript/pull/7783

#### :nail_care: Polish

- Allow skipping the leading pipe in variant definition with a leading constructor with an attribute. https://github.com/rescript-lang/rescript/pull/7782
- Better error message (and recovery) when using a keyword as a record field name. https://github.com/rescript-lang/rescript/pull/7784

# 12.0.0-beta.6

#### :boom: Breaking Change

- `rescript format` no longer accepts `--all`. All (non-dev) files of the current rescript.json are now formatted by default. https://github.com/rescript-lang/rescript/pull/7752

#### :rocket: New Feature

- Add new Stdlib helpers: `String.capitalize`, `String.isEmpty`, `Dict.size`, `Dict.isEmpty`, `Array.isEmpty`, `Map.isEmpty`, `Set.isEmpty`. https://github.com/rescript-lang/rescript/pull/7516

#### :bug: Bug fix

- Fix issue with ast conversion (for ppx use) on functions with attributes on first argument. https://github.com/rescript-lang/rescript/pull/7761

#### :nail_care: Polish

- `rescript format` now has a `--dev` flag that works similar to `rescript clean`. https://github.com/rescript-lang/rescript/pull/7752
- `rescript clean` now will clean an individual project (see [#7707](https://github.com/rescript-lang/rescript/issues/7707)). https://github.com/rescript-lang/rescript/pull/7752
- `rescript clean` will log multiple `in-source` extensions if present. https://github.com/rescript-lang/rescript/pull/7769

#### :house: Internal

- AST: Use jsx_tag_name instead of Longindent.t to store jsx tag name. https://github.com/rescript-lang/rescript/pull/7760

# 12.0.0-beta.5

#### :bug: Bug fix

- Fix option optimisation that resulted in incorrect JS output. https://github.com/rescript-lang/rescript/pull/7766
- Fix formatting of nested records in `.resi` files. https://github.com/rescript-lang/rescript/pull/7741
- Don't format and don't check formatting of dependencies. https://github.com/rescript-lang/rescript/pull/7748
- Fix `rescript-editor-analysis semanticTokens` returning invalid JSON in certain cases. https://github.com/rescript-lang/rescript/pull/7750

#### :memo: Documentation

- Update jsx schema configuration. https://github.com/rescript-lang/rescript/pull/7755

#### :nail_care: Polish

- Read package name from rescript.json if package.json is absent. https://github.com/rescript-lang/rescript/pull/7746

#### :house: Internal

- Add token viewer to `res_parser`. https://github.com/rescript-lang/rescript/pull/7751
- Refactor jsx mode in Scanner. https://github.com/rescript-lang/rescript/pull/7751

# 12.0.0-beta.4

#### :bug: Bug fix

- Fix error message that falsely suggested using coercion when it wouldn't work. https://github.com/rescript-lang/rescript/pull/7721
- Fix hang in `rescript-editor-analysis.exe codeAction` that sometimes prevented ReScript files from being saved in VS Code. https://github.com/rescript-lang/rescript/pull/7731
- Fix formatter removing () from functor type. https://github.com/rescript-lang/rescript/pull/7735
- Rewatch: don't compile dev-dependencies of non local dependencies with `--dev`. https://github.com/rescript-lang/rescript/pull/7736

#### :nail_care: Polish

- Apply heuristic to suggest using JSX fragments where we guess that might be what the user wanted. https://github.com/rescript-lang/rescript/pull/7714
- Show deprecation warnings for `bs-dependencies` etc. for local dependencies only. https://github.com/rescript-lang/rescript/pull/7724
- Add check for minimum required node version. https://github.com/rescript-lang/rescript/pull/7723
- Use more optional args in stdlib and deprecate some functions. https://github.com/rescript-lang/rescript/pull/7730
- Improve error message for when trying to do dot access on an option/array. https://github.com/rescript-lang/rescript/pull/7732

# 12.0.0-beta.3

#### :boom: Breaking Change

- `Result.getOrThrow` now throws a JS error instead of a `Not_found` ReScript exception. https://github.com/rescript-lang/rescript/pull/7630
- Remove `rescript dump` command. `bsc` can be used directly to dump the contents of a `.cmi` file instead if needed. https://github.com/rescript-lang/rescript/pull/7710

#### :rocket: New Feature

- Add optional `message` argument to `Result.getOrThrow` and improve default error message. https://github.com/rescript-lang/rescript/pull/7630
- Add `RegExp.escape` binding. https://github.com/rescript-lang/rescript/pull/7695

#### :bug: Bug fix

- Fix `--create-sourcedirs` generation with for a single project. https://github.com/rescript-lang/rescript/pull/7671
- Fix rewatch not recompiling on changes on Windows. https://github.com/rescript-lang/rescript/pull/7690
- Fix locations of regex literals. https://github.com/rescript-lang/rescript/pull/7683
- Fix async React component compilation. https://github.com/rescript-lang/rescript/pull/7704
- Fix `@this` with `async` keyword. https://github.com/rescript-lang/rescript/pull/7702

#### :nail_care: Polish

- Configuration fields `bs-dependencies`, `bs-dev-dependencies` and `bsc-flags` are now deprecated in favor of `dependencies`, `dev-dependencies` and `compiler-flags`. https://github.com/rescript-lang/rescript/pull/7658
- Better error message if platform binaries package is not found. https://github.com/rescript-lang/rescript/pull/7698
- Hint in error for string constants matching expected variant/polyvariant constructor. https://github.com/rescript-lang/rescript/pull/7711
- Polish arity mismatch error message a bit. https://github.com/rescript-lang/rescript/pull/7709
- Suggest related functions with the expected arity in errors when it makes sense. https://github.com/rescript-lang/rescript/pull/7712
- Improve error when a constructor expects an inline record. https://github.com/rescript-lang/rescript/pull/7713
- Remove `@meth` attribute. https://github.com/rescript-lang/rescript/pull/7684

#### :house: Internal

- Add rust linting to CI with `clippy`. https://github.com/rescript-lang/rescript/pull/7675
- AST: use `Typ.arrows` for creation, after the refactoring of arrow types. https://github.com/rescript-lang/rescript/pull/7662
- Don't skip Stdlib docstring tests. https://github.com/rescript-lang/rescript/pull/7694
- Remove all leftovers of `pinned-dependencies` handling. https://github.com/rescript-lang/rescript/pull/7686
- Add `rust-version` field to Rewatch's `Cargo.toml`. https://github.com/rescript-lang/rescript/pull/7701
- Rewatch: remove support for .ml(i) and .re(i). https://github.com/rescript-lang/rescript/pull/7727

# 12.0.0-beta.2

#### :boom: Breaking Change

- Rust implementation of the `rescript format` command. Command line options changed from `-all`, `-check` and `-stdin` to `--all`, `--check` and `--stdin` compared to the legacy implementation. https://github.com/rescript-lang/rescript/pull/7603

#### :rocket: New Feature

- Add experimental command to `rescript-tools` for extracting all ReScript code blocks from markdown, either a md-file directly, or inside of docstrings in ReScript code. https://github.com/rescript-lang/rescript/pull/7623

#### :bug: Bug fix

- Fix `typeof` parens on functions. https://github.com/rescript-lang/rescript/pull/7643
- Rewatch: Add `--dev` flag to clean command. https://github.com/rescript-lang/rescript/pull/7622
- Rewatch: Use root package suffix in clean log messages. https://github.com/rescript-lang/rescript/pull/7648
- Fix inside comment printing for empty dict. https://github.com/rescript-lang/rescript/pull/7654
- Fix I/O error message when trying to extract extra info from non-existing file. https://github.com/rescript-lang/rescript/pull/7656
- Fix fatal error when JSX expression used without configuring JSX in `rescript.json`. https://github.com/rescript-lang/rescript/pull/7656
- Rewatch: Only allow access to `"bs-dev-dependencies"` from `"type": "dev"` source files. https://github.com/rescript-lang/rescript/pull/7650
- Fix comment attached to array element. https://github.com/rescript-lang/rescript/pull/7672
- Rewatch: fix compilation of files starting with a lowercase letter. https://github.com/rescript-lang/rescript/pull/7700

#### :nail_care: Polish

- Add missing backtick and spaces to `Belt.Map.map` doc comment. https://github.com/rescript-lang/rescript/pull/7632
- AST: store the attributes directly on function arguments. https://github.com/rescript-lang/rescript/pull/7660

#### :house: Internal

- Remove internal/unused `-bs-v` flag. https://github.com/rescript-lang/rescript/pull/7627
- Remove unused `-bs-D` and `-bs-list-conditionals` flags. https://github.com/rescript-lang/rescript/pull/7631
- Remove obsolete jsx options. https://github.com/rescript-lang/rescript/pull/7633
- Remove obsolete option `-bs-unsafe-empty-array`. https://github.com/rescript-lang/rescript/pull/7635
- Clean up `config.ml`. https://github.com/rescript-lang/rescript/pull/7636
- Rewatch: simplify getting bsc path. https://github.com/rescript-lang/rescript/pull/7634
- Rewatch: only get `"type": "dev"` source files for local packages. https://github.com/rescript-lang/rescript/pull/7646
- Rewatch: add support for `rescript -w` for compatibility. https://github.com/rescript-lang/rescript/pull/7649
- Fix dev container. https://github.com/rescript-lang/rescript/pull/7700

# 12.0.0-beta.1

#### :rocket: New Feature

- Add experimental command to `rescript-tools` for formatting all ReScript code blocks in markdown. Either in a markdown file directly, or inside of docstrings in ReScript code. https://github.com/rescript-lang/rescript/pull/7598
- Add `String.getSymbolUnsafe` back to Stdlib. https://github.com/rescript-lang/rescript/pull/7626

#### :nail_care: Polish

- Add a warning if the name in package.json does not match the name in rescript.json. https://github.com/rescript-lang/rescript/pull/7604

#### :house: Internal

- Remove uncurried handling from rewatch. https://github.com/rescript-lang/rescript/pull/7625

# 12.0.0-alpha.15

#### :boom: Breaking Change

- New `rewatch` based build system. https://github.com/rescript-lang/rescript/pull/7551 https://github.com/rescript-lang/rescript/pull/7593
  - The new `rewatch` based build system is now the default and is exposed through the `rescript` command. The `rewatch` command has been removed.
  - The previous Ninja-based build system is now available via the `rescript legacy` subcommand.
  - Argument `--compiler-args` is now a subcommand `compiler-args`.
- Remove `String.getSymbol`, `String.getSymbolUnsafe`, `String.setSymbol` from standard library. https://github.com/rescript-lang/rescript/pull/7571

#### :bug: Bug fix

- Ignore inferred arity in functions inside `%raw` functions, leaving to `%ffi` the responsibility to check the arity since it gives an error in case of mismatch. https://github.com/rescript-lang/rescript/pull/7542
- Pass the rewatch exit code through in wrapper script. https://github.com/rescript-lang/rescript/pull/7565
- Prop punning when types don't match results in `I/O error: _none_: No such file or directory`. https://github.com/rescript-lang/rescript/pull/7533
- Pass location to children prop in jsx ppx. https://github.com/rescript-lang/rescript/pull/7540
- Fix crash when `-bs-g` is used with untagged variants. https://github.com/rescript-lang/rescript/pull/7575
- Fix issue with preserve mode where `jsx` is declared as an external without a `@module` attribute. https://github.com/rescript-lang/rescript/pull/7591
- Rewatch: don't add deps to modules that are in packages that are not a dependency. https://github.com/rescript-lang/rescript/pull/7612
- Rewatch: fix non-unicode stderr. https://github.com/rescript-lang/rescript/pull/7613
- Fix rewatch considering warning configs of non-local dependencies. https://github.com/rescript-lang/rescript/pull/7614
- Rewatch: fix panic if package.json name different from module name. https://github.com/rescript-lang/rescript/pull/7616
- Fix finding the standard library for pnpm. https://github.com/rescript-lang/rescript/pull/7615

#### :nail_care: Polish

- Better error message for when trying to await something that is not a promise. https://github.com/rescript-lang/rescript/pull/7561
- Better error messages for object field missing and object field type mismatches. https://github.com/rescript-lang/rescript/pull/7580
- Better error messages for when polymorphic variants does not match for various reasons. https://github.com/rescript-lang/rescript/pull/7596
- Improved completions for inline records. https://github.com/rescript-lang/rescript/pull/7601
- Add `OrThrow` aliases for `Belt` functions ending with `Exn`. https://github.com/rescript-lang/rescript/pull/7581, https://github.com/rescript-lang/rescript/pull/7590 The following aliases have been added:
  - `Belt.Array.getOrThrow`
  - `Belt.Array.setOrThrow`
  - `Belt.Map.getOrThrow`
  - `Belt.MutableMap.getOrThrow`
  - `Belt.Set.getOrThrow`
  - `Belt.MutableSet.getOrThrow`
  - `Belt.List.getOrThrow`
  - `Belt.List.tailOrThrow`
  - `Belt.List.headOrThrow`
  - `Belt.MutableQueue.peekOrThrow`
  - `Belt.MutableQueue.popOrThrow`
  - `Belt.Option.getOrThrow`
  - `Belt.Result.getOrThrow`

#### :house: Internal

- Remove `@return(undefined_to_opt)` and `%undefined_to_opt` primitive. https://github.com/rescript-lang/rescript/pull/7462
- Migrate rewatch to Rust 2024 edition. https://github.com/rescript-lang/rescript/pull/7602

# 12.0.0-alpha.14

#### :boom: Breaking Change

- `Iterator.forEach` now emits `Iterator.prototype.forEach` call. https://github.com/rescript-lang/rescript/pull/7506
- Rename functions ending with `Exn` to end with `OrThrow`. The old `Exn` functions are now deprecated:
  - `Bool.fromStringExn` → `Bool.fromStringOrThrow`
  - `BigInt.fromStringExn` → `BigInt.fromStringOrThrow`
  - `JSON.parseExn` → `JSON.parseOrThrow`
  - Changed `BigInt.fromFloat` to return an option rather than throwing an error.
  - Added `BigInt.fromFloatOrThrow`
  - `Option.getExn` → `Option.getOrThrow`
  - `Null.getExn` → `Null.getOrThrow`
  - `Nullable.getExn` → `Nullable.getOrThrow`
  - `Result.getExn` → `Result.getOrThrow`
  - `List.getExn` → `List.getOrThrow`
  - `List.tailExn` → `List.tailOrThrow`
  - `List.headExn` → `List.headOrThrow`
  - Old functions remain available but are marked as deprecated with guidance to use the new `OrThrow` variants.
  - https://github.com/rescript-lang/rescript/pull/7518, https://github.com/rescript-lang/rescript/pull/7554

#### :rocket: New Feature

- Add `RegExp.flags`. https://github.com/rescript-lang/rescript/pull/7461
- Add `Array.findLast`, `Array.findLastWithIndex`, `Array.findLastIndex`, `Array.findLastIndexWithIndex` and `Array.findLastIndexOpt`. https://github.com/rescript-lang/rescript/pull/7503
- Add `options` argument to `Console.dir`. https://github.com/rescript-lang/rescript/pull/7504
- Show variant constructor's inline record types on hover. https://github.com/rescript-lang/rescript/pull/7519
- Add additional `Iterator.prototype` bindings to `runtime/Stdlib_Iterator.res`. https://github.com/rescript-lang/rescript/pull/7506

#### :bug: Bug fix

- `rescript-tools doc` no longer includes shadowed bindings in its output. https://github.com/rescript-lang/rescript/pull/7497
- Treat `throw` like `raise` in analysis. https://github.com/rescript-lang/rescript/pull/7521
- Fix `index out of bounds` exception thrown in rare cases by `rescript-editor-analysis.exe codeAction` command. https://github.com/rescript-lang/rescript/pull/7523
- Don't produce duplicate type definitions for recursive types on hover. https://github.com/rescript-lang/rescript/pull/7524
- Prop punning when types don't match results in `I/O error: _none_: No such file or directory`. https://github.com/rescript-lang/rescript/pull/7533
- Fix partial application with user-defined function types. https://github.com/rescript-lang/rescript/pull/7548
- Fix doc comment before variant throwing syntax error. https://github.com/rescript-lang/rescript/pull/7535
- Fix apparent non-determinism in generated code for pattern matching. https://github.com/rescript-lang/rescript/pull/7557

#### :nail_care: Polish

- Suggest awaiting promise before using it when types mismatch. https://github.com/rescript-lang/rescript/pull/7498
- Complete from `RegExp` stdlib module for regexes. https://github.com/rescript-lang/rescript/pull/7425
- Allow oneliner formatting when including module with single type alias. https://github.com/rescript-lang/rescript/pull/7502
- Improve error messages for JSX type mismatches, passing objects where record is expected, passing array literal where tuple is expected, and more. https://github.com/rescript-lang/rescript/pull/7500
- Show in error messages when coercion can be used to fix a type mismatch. https://github.com/rescript-lang/rescript/pull/7505
- Remove deprecated pipe last (`|>`) syntax. https://github.com/rescript-lang/rescript/pull/7512
- Improve error message for pipe (`->`) syntax. https://github.com/rescript-lang/rescript/pull/7520
- Improve a few error messages around various subtyping issues. https://github.com/rescript-lang/rescript/pull/7404
- In module declarations, accept the invalid syntax `M = {...}` and format it to `M : {...}`. https://github.com/rescript-lang/rescript/pull/7527
- Improve doc comment formatting to match the style of multiline comments. https://github.com/rescript-lang/rescript/pull/7529
- Improve error messages around type mismatches for try/catch, if, for, while, and optional record fields + optional function arguments. https://github.com/rescript-lang/rescript/pull/7522
- Sync reanalyze with the new APIs around exception. https://github.com/rescript-lang/rescript/pull/7536
- Improve array pattern spread error message. https://github.com/rescript-lang/rescript/pull/7549
- Sync API docs with rescript-lang.org on release. https://github.com/rescript-lang/rescript/pull/7555

#### :house: Internal

- Refactor the ast for record expressions and patterns. https://github.com/rescript-lang/rescript/pull/7528
- Editor: add completions from included modules. https://github.com/rescript-lang/rescript/pull/7515
- Add `-editor-mode` arg to `bsc` for doing special optimizations only relevant to the editor tooling. https://github.com/rescript-lang/rescript/pull/7541

# 12.0.0-alpha.13

#### :boom: Breaking Change

- Rename `JsError` to `JsExn` and error modules cleanup. https://github.com/rescript-lang/rescript/pull/7408
- Make `BigInt.fromFloat` return an option rather than throwing an error in case it's passed a value with a decimal value. https://github.com/rescript-lang/rescript/pull/7419

#### :rocket: New Feature

- Add shift (`<<`, `>>`, `>>>`) operators for `int` and `bigint`. https://github.com/rescript-lang/rescript/pull/7183
- Add bitwise AND (`&`) operator for `int` and `bigint`. https://github.com/rescript-lang/rescript/pull/7415
- Add bitwise NOT (`~`) operator for `int` and `bigint`. https://github.com/rescript-lang/rescript/pull/7418
- Significantly reduced the download size by splitting binaries into optional platform-specific dependencies (e.g, `@rescript/linux-x64`). https://github.com/rescript-lang/rescript/pull/7395
- JSX: do not error on ref as prop anymore (which is allowed in React 19). https://github.com/rescript-lang/rescript/pull/7420
- Add new attribute `@notUndefined` for abstract types to prevent unnecessary wrapping with `Primitive_option.some` in JS output. https://github.com/rescript-lang/rescript/pull/7458
- Preserve JSX: enable by adding `"-bs-jsx-preserve"` to `"bsc-flags"` (does require `"jsx": { "version": 4 }`). https://github.com/rescript-lang/rescript/pull/7387
- Add slot prop to `JsxDOM.domProps`. https://github.com/rescript-lang/rescript/pull/7487

#### :bug: Bug fix

- Fix broken `bstracing` CLI location. https://github.com/rescript-lang/rescript/pull/7398
- Fix field flattening optimization to avoid creating unnecessary copies of allocating constants. https://github.com/rescript-lang/rescript-compiler/pull/7421
- Fix leading comments removed when braces inside JSX contains `let` assignment. https://github.com/rescript-lang/rescript/pull/7424
- Fix JSON escaping in code editor analysis: JSON was not always escaped properly, which prevented code actions from being available in certain situations. https://github.com/rescript-lang/rescript/pull/7435
- Fix regression in pattern matching for optional fields containing variants. https://github.com/rescript-lang/rescript/pull/7440
- Fix missing checks for duplicate literals in variants with payloads. https://github.com/rescript-lang/rescript/pull/7441
- Fix printer removing private for empty record. https://github.com/rescript-lang/rescript/pull/7448
- Fix: handle dynamic imports with module aliases. https://github.com/rescript-lang/rescript/pull/7452
- Fix missing unescaping when accessing prop with exotic name. https://github.com/rescript-lang/rescript/pull/7469
- Fix syntax error with mutable nested record. https://github.com/rescript-lang/rescript/pull/7470

#### :house: Internal

- AST: Add bar location to `case`. https://github.com/rescript-lang/rescript/pull/7407
- Clean up lazy from ASTs and back-end. https://github.com/rescript-lang/rescript/pull/7474
- Compile runtime with rewatch and add rewatch tests to the compiler repo. https://github.com/rescript-lang/rescript/pull/7422

#### :nail_care: Polish

- In type errors, recommend stdlib over Belt functions for converting between float/int/string. https://github.com/rescript-lang/rescript/pull/7453
- Remove unused type `Jsx.ref`. https://github.com/rescript-lang/rescript/pull/7459
- Add `@notUndefined` attribute to all relevant abstract types in `Stdlib`. https://github.com/rescript-lang/rescript/pull/7464
- Editor: Add pipe completions from current module. https://github.com/rescript-lang/rescript/pull/7471

# 12.0.0-alpha.12

#### :bug: Bug fix

- Fix node.js `ExperimentalWarning`. https://github.com/rescript-lang/rescript/pull/7379
- Fix issue with gentype and stdlib json. https://github.com/rescript-lang/rescript/pull/7378
- Fix type of `RegExp.Result.matches`. https://github.com/rescript-lang/rescript/pull/7393
- Add optional `flags` argument to `RegExp.fromString` and deprecate `RegExp.fromStringWithFlags`. https://github.com/rescript-lang/rescript/pull/7393

#### :house: Internal

- Better representation of JSX in AST. https://github.com/rescript-lang/rescript/pull/7286
- Clean up default warnings. https://github.com/rescript-lang/rescript/pull/7413

#### :nail_care: Polish

- Improve error message for missing value when the identifier is also the name of a module in scope. https://github.com/rescript-lang/rescript/pull/7384
- Upgrade Flow parser to 0.267.0. https://github.com/rescript-lang/rescript/pull/7390
- Move `Lazy` module to Stdlib. https://github.com/rescript-lang/rescript/pull/7399

# 12.0.0-alpha.11

#### :bug: Bug fix

- Fix `Error.fromException`. https://github.com/rescript-lang/rescript/pull/7364
- Fix signature of `throw`. https://github.com/rescript-lang/rescript/pull/7365
- Fix formatter adds superfluous parens in pipe chain. https://github.com/rescript-lang/rescript/pull/7370

#### :house: Internal

- Remove `Stdlib_Char` module for now. https://github.com/rescript-lang/rescript/pull/7367
- Convert internal JavaScript codebase into ESM, ReScript package itself is now ESM (`"type": "module"`). https://github.com/rescript-lang/rescript/pull/6899
- Add built-in support for the JavaScript `in` operator. https://github.com/rescript-lang/rescript/pull/7342
- AST cleanup: add `Pexp_await` ast node instead of `res.await` attribute. (The attribute is still used for await on modules currently). https://github.com/rescript-lang/rescript/pull/7368

#### :nail_care: Polish

- More deprecations in `Pervasives`; add `Stdlib.Pair` and `Stdlib.Int.Ref`. https://github.com/rescript-lang/rescript/pull/7371

# 12.0.0-alpha.10

#### :rocket: New Feature

- Add `Dict.has` and double `Dict.forEachWithKey`/`Dict.mapValues` performance. https://github.com/rescript-lang/rescript/pull/7316
- Add popover attributes to `JsxDOM.domProps`. https://github.com/rescript-lang/rescript/pull/7317
- Add `Array.removeInPlace` helper based on `splice`. https://github.com/rescript-lang/rescript/pull/7321
- Add `inert` attribute to `JsxDOM.domProps`. https://github.com/rescript-lang/rescript/pull/7326
- Make reanalyze exception tracking work with the new stdlib. https://github.com/rescript-lang/rescript/pull/7328
- Fix `Pervasive.max` using boolean comparison for floats. https://github.com/rescript-lang/rescript/pull/7333
- Experimental: Support nested/inline record types - records defined inside of other records, without needing explicit separate type definitions. https://github.com/rescript-lang/rescript/pull/7241
- Add unified exponentiation (`**`) operator for numeric types using ES7 `**`. https://github.com/rescript-lang/rescript-compiler/pull/7153
- Rename `raise` to `throw` to align with JavaScript vocabulary. `raise` has been deprecated. https://github.com/rescript-lang/rescript/pull/7346
- Add unified bitwise (`^`) operator. https://github.com/rescript-lang/rescript/pull/7216
- Stdlib: rename binary operations to match JavaScript terms. https://github.com/rescript-lang/rescript/pull/7353

#### :boom: Breaking Change

- Replace `~date` with `~day` in `Date.make`. https://github.com/rescript-lang/rescript/pull/7324
- Remove `-bs-jsx-mode`. https://github.com/rescript-lang/rescript/pull/7327
- Drop Node.js version <20 support, as it is reaching End-of-Life. https://github.com/rescript-lang/rescript-compiler/pull/7354
- Treat `int` multiplication as a normal int32 operation instead of using `Math.imul`. https://github.com/rescript-lang/rescript/pull/7358

#### :house: Internal

- Clean up legacy tags handling. https://github.com/rescript-lang/rescript/pull/7309
- Use Yarn (Berry) workspaces for internal tooling. https://github.com/rescript-lang/rescript/pull/7309

#### :nail_care: Polish

- Deprecate `JSON.Classify.classify`. https://github.com/rescript-lang/rescript/pull/7315
- Hide stdlib modules in output. https://github.com/rescript-lang/rescript/pull/7305
- Deprecate unsafe host-specific bindings from stdlib. https://github.com/rescript-lang/rescript/pull/7334
- Make unsafe function names consistent in `Stdlib.String`. https://github.com/rescript-lang/rescript/pull/7337
- `rescript` package does not trigger `postinstall` script anymore. https://github.com/rescript-lang/rescript/pull/7350
- Add Stdlib `Bool` and `Char` modules and improve Pervasives deprecation messages. https://github.com/rescript-lang/rescript/pull/7361

#### :bug: Bug fix

- Fix recursive untagged variant type checking by delaying well-formedness checks until environment construction completes. https://github.com/rescript-lang/rescript/pull/7320
- Fix incorrect expansion of polymorphic return types in uncurried function applications. https://github.com/rescript-lang/rescript/pull/7338

# 12.0.0-alpha.9

#### :boom: Breaking Change

- Clean list API. https://github.com/rescript-lang/rescript/pull/7290

#### :nail_care: Polish

- Allow single newline in JSX. https://github.com/rescript-lang/rescript/pull/7269
- Editor: Always complete from Core first. Use actual native regex syntax in code snippets for regexps. https://github.com/rescript-lang/rescript/pull/7295
- Add `type t` to Stdlib modules. https://github.com/rescript-lang/rescript/pull/7302
- Gentype: handle null/nullable/undefined from Stdlib. https://github.com/rescript-lang/rescript/pull/7132

#### :bug: Bug fix

- Fix async context checking for module await. https://github.com/rescript-lang/rescript/pull/7271
- Fix `%external` extension. https://github.com/rescript-lang/rescript/pull/7272
- Fix issue with type environment for unified ops. https://github.com/rescript-lang/rescript/pull/7277
- Fix completion for application with tagged template. https://github.com/rescript-lang/rescript/pull/7278
- Fix error message for arity in the presence of optional arguments. https://github.com/rescript-lang/rescript/pull/7284
- Fix issue in functors with more than one argument (which are curried): emit nested function always. https://github.com/rescript-lang/rescript/pull/7273
- Fix dot completion issue with React primitives. https://github.com/rescript-lang/rescript/pull/7292
- Stdlib namespace for Core modules (fixes name clashes with user modules). https://github.com/rescript-lang/rescript/pull/7285
- Fix runtime type check for Object in untagged variants when one variant case is `null`. https://github.com/rescript-lang/rescript/pull/7303
- Fix files that were being truncated when sent to the CDN over FTP. https://github.com/rescript-lang/rescript/pull/7306
- Fix better editor completion for applications. https://github.com/rescript-lang/rescript/pull/7291
- Fix `@react.componentWithProps` no longer works with `@directive("'use memo'")`. https://github.com/rescript-lang/rescript/pull/7300

#### :house: Internal

- Remove `ignore` in `res_scanner.ml`. https://github.com/rescript-lang/rescript/pull/7280
- Use the new stdlib modules in the analysis tests. https://github.com/rescript-lang/rescript/pull/7295
- Build with OCaml 5.3.0. https://github.com/rescript-lang/rescript/pull/7294
- Simplify `JSON.Decode` implementation. https://github.com/rescript-lang/rescript/pull/7304

# 12.0.0-alpha.8

#### :bug: Bug fix

- Editor: Fix issue where pipe completions would not trigger with generic type arguments. https://github.com/rescript-lang/rescript/pull/7231
- Fix leftover `assert false` in code for `null != undefined`. https://github.com/rescript-lang/rescript/pull/7232
- Editor: Fix issue where completions would not show up inside of object bodies. https://github.com/rescript-lang/rescript/pull/7230
- Fix issue with pattern matching empty list which interferes with boolean optimisations. https://github.com/rescript-lang/rescript/pull/7237
- Fix Cannot combine `@react.component` and `@directive`. https://github.com/rescript-lang/rescript/pull/7260
- Fix issue where attributes on an application were not preserved by the AST conversion for ppx. https://github.com/rescript-lang/rescript/pull/7262

#### :house: Internal

- AST cleanup: Prepare for ast async cleanup: Refactor code for `@res.async` payload handling and clean up handling of type and term parameters, so that now each `=>` in a function definition corresponds to a function. https://github.com/rescript-lang/rescript/pull/7223
- AST: always put type parameters first in function definitions. https://github.com/rescript-lang/rescript/pull/7233
- AST cleanup: Remove `@res.async` attribute from the internal representation, and add a flag to untyped and typed ASTs instead. https://github.com/rescript-lang/rescript/pull/7234
- AST cleanup: Remove unused `expression_desc.Pexp_new`, `expression_desc.Pexp_setinstvar`, `expression_desc.Pexp_override`, `expression_desc.Pexp_poly`, `exp_extra.Texp_poly`, `expression_desc.Texp_new`, `expression_desc.Texp_setinstvar`, `expression_desc.Texp_override` & `expression_desc.Texp_instvar` from AST. https://github.com/rescript-lang/rescript/pull/7239
- AST cleanup: Remove `@res.partial` attribute from the internal representation, and add a flag to untyped and typed ASTs instead. https://github.com/rescript-lang/rescript/pull/7238 https://github.com/rescript-lang/rescript/pull/7240
- AST cleanup: Remove unused `structure_item_desc.Pstr_class`, `signature_item_desc.Psig_class`, `structure_item_desc.Pstr_class_type`, `signature_item_desc.Psig_class_type`, `structure_item_desc.Tstr_class`, `structure_item_desc.Tstr_class_type`, `signature_item_desc.Tsig_class`, `signature_item_desc.Tsig_class_type` from AST. https://github.com/rescript-lang/rescript/pull/7242
- AST cleanup: remove `|.` and rename `|.` to `->` in the internal representation for the pipe operator. https://github.com/rescript-lang/rescript/pull/7244
- AST cleanup: represent concatenation (`++`) and (dis)equality operators (`==`, `===`, `!=`, `!==`) just like in the syntax. https://github.com/rescript-lang/rescript/pull/7248
- AST cleanup: use inline record for `Ptyp_arrow`. https://github.com/rescript-lang/rescript/pull/7250
- Playground: Bundle stdlib runtime so that the playground can execute functions from Core/Belt/Js. https://github.com/rescript-lang/rescript/pull/7255
- AST cleanup: Remove `res.namedArgLoc` attribute and store the location information directly into the label. https://github.com/rescript-lang/rescript/pull/7247

#### :nail_care: Polish

- Rewatch 1.0.10. https://github.com/rescript-lang/rescript/pull/7259

# 12.0.0-alpha.7

#### :bug: Bug fix

- Editor: Fix issue where completions would stop working in some scenarios with inline records. https://github.com/rescript-lang/rescript/pull/7227

#### :nail_care: Polish

- Add all standard CSS properties to `JsxDOMStyle`. https://github.com/rescript-lang/rescript/pull/7205

#### :house: Internal

- AST cleanup: use inline record for Pexp_fun. https://github.com/rescript-lang/rescript/pull/7213
- Add support for "dot completion everywhere" (ported from https://github.com/rescript-lang/rescript-vscode/pull/1054). https://github.com/rescript-lang/rescript/pull/7226
- Add assertions to stdlib docstring examples. Extract examples into Mocha tests, compile and run the tests in CI. https://github.com/rescript-lang/rescript/pull/7219

# 12.0.0-alpha.6

#### :rocket: New Feature

- Add `Option.all` & `Result.all` helpers. https://github.com/rescript-lang/rescript/pull/7181
- Add `@react.componentWithProps` for React component functions taking a props record instead of labeled arguments. https://github.com/rescript-lang/rescript/pull/7203

#### :bug: Bug fix

- Fix exponential notation syntax. https://github.com/rescript-lang/rescript/pull/7174
- Fix bug where a ref assignment is moved ouside a conditional. https://github.com/rescript-lang/rescript/pull/7176
- Fix nullable to opt conversion. https://github.com/rescript-lang/rescript/pull/7193
- Raise error when defining external React components with `@react.componentWithProps`. https://github.com/rescript-lang/rescript/pull/7217
- Fix formatter handling of wildcard in pattern matching records with no fields specified. https://github.com/rescript-lang/rescript/pull/7224

#### :house: Internal

- Use latest compiler for tests. https://github.com/rescript-lang/rescript/pull/7186
- Added infra to modernise AST: theres' Parsetree, Parsetree0 (legacy), and conversion functions to keep compatibility with PPX. https://github.com/rescript-lang/rescript/pull/7185
- AST cleanup: remove exp object and exp unreachable. https://github.com/rescript-lang/rescript/pull/7189
- AST cleanup: explicit representation for optional record fields in types. https://github.com/rescript-lang/rescript/pull/7190 https://github.com/rescript-lang/rescript/pull/7191
- AST cleanup: first-class expression and patterns for records with optional fields. https://github.com/rescript-lang/rescript/pull/7192
- AST cleanup: Represent the arity of uncurried function definitions directly in the AST. https://github.com/rescript-lang/rescript/pull/7197
- AST cleanup: Remove Pexp_function from the AST. https://github.com/rescript-lang/rescript/pull/7198
- Remove unused code from Location and Rescript_cpp modules. https://github.com/rescript-lang/rescript/pull/7150
- Build with OCaml 5.2.1. https://github.com/rescript-lang/rescript-compiler/pull/7201
- AST cleanup: Remove `Function$` entirely for function definitions. https://github.com/rescript-lang/rescript/pull/7200
- AST cleanup: store arity in function type. https://github.com/rescript-lang/rescript/pull/7195
- AST cleanup: remove explicit uses of `function$` in preparation for removing the type entirely. https://github.com/rescript-lang/rescript/pull/7206
- AST cleanup: remove `function$` entirely. https://github.com/rescript-lang/rescript/pull/7208

# 12.0.0-alpha.5

#### :rocket: New Feature

- Introduce "Unified operators" for arithmetic operators (`+`, `-`, `*`, `/`, `mod`). https://github.com/rescript-lang/rescript-compiler/pull/7057
- Add remainder (`%`, aka modulus) operator. https://github.com/rescript-lang/rescript-compiler/pull/7152

#### :bug: Bug fix

- Fix and clean up boolean and/or optimizations. https://github.com/rescript-lang/rescript-compiler/pull/7134 https://github.com/rescript-lang/rescript-compiler/pull/7151
- Fix identifiers with name `arguments` and `eval` to be mangled. https://github.com/rescript-lang/rescript/pull/7163

#### :nail_care: Polish

- Improve code generation for pattern matching of untagged variants. https://github.com/rescript-lang/rescript-compiler/pull/7128
- Improve negation handling in combination with and/or to simplify generated code (especially coming out of pattern matching). https://github.com/rescript-lang/rescript-compiler/pull/7138
- Optimize JavaScript code generation by using `x == null` checks and improving type-based optimizations for string/number literals. https://github.com/rescript-lang/rescript-compiler/pull/7141
- Improve pattern matching on optional fields. https://github.com/rescript-lang/rescript-compiler/pull/7143 https://github.com/rescript-lang/rescript-compiler/pull/7144
- Optimize compilation of switch statements for untagged variants when there are no literal cases. https://github.com/rescript-lang/rescript-compiler/pull/7135
- Further improve boolean optimizations. https://github.com/rescript-lang/rescript-compiler/pull/7149
- Simplify code generated for conditionals. https://github.com/rescript-lang/rescript-compiler/pull/7151

#### :house: Internal

- Move rescript-editor-analysis and rescript-tools into compiler repo. https://github.com/rescript-lang/rescript-compiler/pull/7000

# 12.0.0-alpha.4

#### :boom: Breaking Change

- OCaml compatibility in the stdlib and primitives are dropped/deprecated. https://github.com/rescript-lang/rescript-compiler/pull/6984
- Remove JSX v3. https://github.com/rescript-lang/rescript-compiler/pull/7072
- Remove js_cast.res. https://github.com/rescript-lang/rescript-compiler/pull/7075

#### :rocket: New Feature

- Use FORCE_COLOR environmental variable to force colorized output. https://github.com/rescript-lang/rescript-compiler/pull/7033
- Allow spreads of variants in patterns (`| ...someVariant as v => `) when the variant spread is a subtype of the variant matched on. https://github.com/rescript-lang/rescript-compiler/pull/6721
- Fix the issue where dynamic imports are not working for function-defined externals. https://github.com/rescript-lang/rescript-compiler/pull/7060
- Allow pattern matching on dicts. `switch someDict { | dict{"one": 1} => Js.log("one is one") }`. https://github.com/rescript-lang/rescript-compiler/pull/7059
- "ReScript Core" standard library is now included in the `rescript` npm package. https://github.com/rescript-lang/rescript-compiler/pull/7108 https://github.com/rescript-lang/rescript-compiler/pull/7116
- Handle absolute filepaths in gentype. https://github.com/rescript-lang/rescript-compiler/pull/7104

#### :bug: Bug fix

- Fix tuple coercion. https://github.com/rescript-lang/rescript-compiler/pull/7024
- Fix attribute printing. https://github.com/rescript-lang/rescript-compiler/pull/7025
- Fix "rescript format" with many files. https://github.com/rescript-lang/rescript-compiler/pull/7081
- Fix bigint max, min. https://github.com/rescript-lang/rescript-compiler/pull/7088
- Fix parsing issue with nested variant pattern type spreads. https://github.com/rescript-lang/rescript-compiler/pull/7080
- Fix JSX settings inheritance: only 'version' propagates to dependencies, preserving their 'mode' and 'module'. https://github.com/rescript-lang/rescript-compiler/pull/7094
- Fix variant cast to int. https://github.com/rescript-lang/rescript-compiler/pull/7058
- Fix comments formatted away in function without arguments. https://github.com/rescript-lang/rescript-compiler/pull/7095
- Fix genType JSX component compilation. https://github.com/rescript-lang/rescript-compiler/pull/7107

#### :nail_care: Polish

- Add some context to error message for unused variables. https://github.com/rescript-lang/rescript-compiler/pull/7050
- Improve error message when passing `children` prop to a component that doesn't accept it. https://github.com/rescript-lang/rescript-compiler/pull/7044
- Improve error messages for pattern matching on option vs non-option, and vice versa. https://github.com/rescript-lang/rescript-compiler/pull/7035
- Improve bigint literal comparison. https://github.com/rescript-lang/rescript-compiler/pull/7029
- Improve output of `@variadic` bindings. https://github.com/rescript-lang/rescript-compiler/pull/7030
- Improve error messages around JSX components. https://github.com/rescript-lang/rescript-compiler/pull/7038
- Improve output of record copying. https://github.com/rescript-lang/rescript-compiler/pull/7043
- Provide additional context in error message when `unit` is expected. https://github.com/rescript-lang/rescript-compiler/pull/7045
- Improve error message when passing an object where a record is expected. https://github.com/rescript-lang/rescript-compiler/pull/7101

#### :house: Internal

- Remove uncurried flag from bsb. https://github.com/rescript-lang/rescript-compiler/pull/7049
- Build runtime/stdlib files with rescript/bsb instead of ninja.js. https://github.com/rescript-lang/rescript-compiler/pull/7063
- Build tests with bsb and move them out of jscomp. https://github.com/rescript-lang/rescript-compiler/pull/7068
- Run `build_tests` on Windows. https://github.com/rescript-lang/rescript-compiler/pull/7065
- Rename folder "jscomp" to "compiler". https://github.com/rescript-lang/rescript-compiler/pull/7086
- Disable -bs-cross-module-opt for tests. https://github.com/rescript-lang/rescript-compiler/pull/7071
- Move `ounit_tests` into the `tests` folder. https://github.com/rescript-lang/rescript-compiler/pull/7096
- Move `syntax_tests` into the `tests` folder. https://github.com/rescript-lang/rescript-compiler/pull/7090 https://github.com/rescript-lang/rescript-compiler/pull/7097
- Capitalize runtime filenames. https://github.com/rescript-lang/rescript-compiler/pull/7110
- Build mocha tests as esmodule / .mjs. https://github.com/rescript-lang/rescript-compiler/pull/7115
- Use dict instead of Dict.t everywhere. https://github.com/rescript-lang/rescript-compiler/pull/7136

# 12.0.0-alpha.3

#### :bug: Bug fix

- Revert "Throws an instance of JavaScript's `new Error()` and adds the extension payload for `cause` option" (https://github.com/rescript-lang/rescript-compiler/pull/6611). https://github.com/rescript-lang/rescript-compiler/pull/7016
- Fix dict literals error. https://github.com/rescript-lang/rescript-compiler/pull/7019

# 12.0.0-alpha.2

#### :rocket: New Feature

- Allow coercing polyvariants to variants when we can guarantee that the runtime representation matches. https://github.com/rescript-lang/rescript-compiler/pull/6981
- Add new dict literal syntax (`dict{"foo": "bar"}`). https://github.com/rescript-lang/rescript-compiler/pull/6774
- Optimize usage of the new dict literal syntax to emit an actual JS object literal. https://github.com/rescript-lang/rescript-compiler/pull/6538

#### :bug: Bug Fix

- Fix issue where long layout break added a trailing comma in partial application `...`. https://github.com/rescript-lang/rescript-compiler/pull/6949
- Fix incorrect format of function under unary operator. https://github.com/rescript-lang/rescript-compiler/pull/6953
- Fix incorrect printing of module binding with signature. https://github.com/rescript-lang/rescript-compiler/pull/6963
- Fix incorrect printing of external with `@as` attribute and `_` placholder (fixed argument). https://github.com/rescript-lang/rescript-compiler/pull/6970
- Disallow spreading anything but regular variants inside of other variants. https://github.com/rescript-lang/rescript-compiler/pull/6980
- Fix comment removed when function signature has `type` keyword. https://github.com/rescript-lang/rescript-compiler/pull/6997
- Fix parse error on doc comment before "and" in type def. https://github.com/rescript-lang/rescript-compiler/pull/7001

#### :house: Internal

- Add dev container. https://github.com/rescript-lang/rescript-compiler/pull/6962
- Convert more tests to the node test runner. https://github.com/rescript-lang/rescript-compiler/pull/6956
- Remove attribute "internal.arity". https://github.com/rescript-lang/rescript-compiler/pull/7004
- Remove dead modules. https://github.com/rescript-lang/rescript-compiler/pull/7008

#### :nail_care: Polish

- Improve formatting in the generated js code. https://github.com/rescript-lang/rescript-compiler/pull/6932
  - `}\ncatch{` -> `} catch {`
  - `for(let i = 0 ,i_finish = r.length; i < i_finish; ++i){` -> `for (let i = 0, i_finish = r.length; i < i_finish; ++i) {`
  - `while(true) {` -> `while (true) {`
  - Fixed tabulation for `switch case` bodies
  - Fixed tabulation for `throw new Error` bodies
  - Removed empty line at the end of `switch` statement
  - Removed empty `default` case from `switch` statement in the generated code
- Optimised the Type Extension runtime code and removed trailing `/1` from `RE_EXN_ID`. https://github.com/rescript-lang/rescript-compiler/pull/6958
- Compact output for anonymous functions. https://github.com/rescript-lang/rescript-compiler/pull/6945 https://github.com/rescript-lang/rescript-compiler/pull/7013
- Rewatch 1.0.9. https://github.com/rescript-lang/rescript-compiler/pull/7010

# 12.0.0-alpha.1

#### :rocket: New Feature

- Allow `@directive` on functions for emitting function level directive code (`let serverAction = @directive("'use server'") (~name) => {...}`). https://github.com/rescript-lang/rescript-compiler/pull/6756
- Add `rewatch` to the npm package as an alternative build tool. https://github.com/rescript-lang/rescript-compiler/pull/6762
- Throws an instance of JavaScript's `new Error()` and adds the extension payload for `cause` option. https://github.com/rescript-lang/rescript-compiler/pull/6611
- Allow free vars in types for type coercion `e :> t`. https://github.com/rescript-lang/rescript-compiler/pull/6828
- Allow `private` in with constraints. https://github.com/rescript-lang/rescript-compiler/pull/6843
- Add regex literals as syntax sugar for `@bs.re`. https://github.com/rescript-lang/rescript-compiler/pull/6776
- Improved mechanism to determine arity of externals, which is consistent however the type is written. https://github.com/rescript-lang/rescript-compiler/pull/6874 https://github.com/rescript-lang/rescript-compiler/pull/6881 https://github.com/rescript-lang/rescript-compiler/pull/6883
- Add `Js.globalThis` object binding. https://github.com/rescript-lang/rescript-compiler/pull/6909

#### :boom: Breaking Change

- Make `j` and `js` allowed names for tag functions. https://github.com/rescript-lang/rescript-compiler/pull/6817
- `lazy` syntax is no longer supported. If you're using it, use `Lazy` module or `React.lazy_` instead. https://github.com/rescript-lang/rescript-compiler/pull/6342
- Remove handling of attributes with `bs.` prefix (`@bs.as` -> `@as` etc.). https://github.com/rescript-lang/rescript-compiler/pull/6643
- Remove obsolete `@bs.open` feature. https://github.com/rescript-lang/rescript-compiler/pull/6629
- Drop Node.js version <18 support, due to it reaching End-of-Life. https://github.com/rescript-lang/rescript-compiler/pull/6429
- Remove deprecated -bs-super-errors option. https://github.com/rescript-lang/rescript-compiler/pull/6814
- Some global names and old keywords are no longer prefixed. https://github.com/rescript-lang/rescript-compiler/pull/6831
- Remove ml parsing tests and conversion from `.ml` to `.res` via format. https://github.com/rescript-lang/rescript-compiler/pull/6848
- Remove support for compiling `.ml` files, and general cleanup. https://github.com/rescript-lang/rescript-compiler/pull/6852
- Remove `rescript convert` subcommand. https://github.com/rescript-lang/rescript-compiler/pull/6860
- Remove support for `@bs.send.pipe`. This also removes all functions in `Js_typed_array` that rely on `@bs.send.pipe`. https://github.com/rescript-lang/rescript-compiler/pull/6858 https://github.com/rescript-lang/rescript-compiler/pull/6891
- Remove deprecated `Js.Vector` and `Js.List`. https://github.com/rescript-lang/rescript-compiler/pull/6900
- Remove support for `%time` extension. https://github.com/rescript-lang/rescript-compiler/pull/6924
- Remove `caml_external_polyfill` module and the related behavior. https://github.com/rescript-lang/rescript-compiler/pull/6925

#### :bug: Bug Fix

- Fix unhandled cases for exotic idents (allow to use exotic PascalCased identifiers for types). https://github.com/rescript-lang/rescript-compiler/pull/6777 https://github.com/rescript-lang/rescript-compiler/pull/6779 https://github.com/rescript-lang/rescript-compiler/pull/6897
- Fix unused attribute check for `@as`. https://github.com/rescript-lang/rescript-compiler/pull/6795
- Reactivate unused attribute check for `@int`. https://github.com/rescript-lang/rescript-compiler/pull/6802
- Fix issue where using partial application `...` can generate code that uses `Curry` at runtime. https://github.com/rescript-lang/rescript-compiler/pull/6872
- Avoid generation of `Curry` with reverse application `|>`. https://github.com/rescript-lang/rescript-compiler/pull/6876
- Fix issue where the internal ppx for pipe `->` would not use uncurried application in uncurried mode. https://github.com/rescript-lang/rescript-compiler/pull/6878

#### :house: Internal

- Build with OCaml 5.2.0. https://github.com/rescript-lang/rescript-compiler/pull/6797
- Convert OCaml codebase to snake case style. https://github.com/rescript-lang/rescript-compiler/pull/6702
- Fix `-nostdlib` internal compiler option. https://github.com/rescript-lang/rescript-compiler/pull/6824
- Remove a number of ast nodes never populated by the .res parser, and resulting dead code. https://github.com/rescript-lang/rescript-compiler/pull/6830
- Remove coercion with 2 types from internal representation. Coercion `e : t1 :> t2` was only supported in `.ml` syntax and never by the `.res` parser. https://github.com/rescript-lang/rescript-compiler/pull/6829
- Convert `caml_format` and `js_math` to `.res`. https://github.com/rescript-lang/rescript-compiler/pull/6834
- Convert `js.ml` files to `.res`. https://github.com/rescript-lang/rescript-compiler/pull/6835
- Remove old `.ml` tests. https://github.com/rescript-lang/rescript-compiler/pull/6847
- Make compiler libs ready for uncurried mode. https://github.com/rescript-lang/rescript-compiler/pull/6861
- Make tests ready for uncurried mode. https://github.com/rescript-lang/rescript-compiler/pull/6862
- Make gentype tests uncurried. https://github.com/rescript-lang/rescript-compiler/pull/6866
- Remove `@@uncurried.swap`, which was used for internal tests. https://github.com/rescript-lang/rescript-compiler/pull/6875
- Build the compiler libraries/tests in uncurried mode. https://github.com/rescript-lang/rescript-compiler/pull/6864
- Ignore `-uncurried` command-line flag. https://github.com/rescript-lang/rescript-compiler/pull/6885
- Cleanup: remove tracking of uncurried state in parser/printer. https://github.com/rescript-lang/rescript-compiler/pull/6888
- Remove `%opaque` primitive. https://github.com/rescript-lang/rescript-compiler/pull/6892
- Reunify JsxC/JsxU -> Jsx etc. https://github.com/rescript-lang/rescript-compiler/pull/6895
- Remove the transformation of `foo(1,2)` into `Js.Internal.opaqueFullApply(Internal.opaque(f), 1, 2)`, and change the back-end to treat all applications as uncurried. https://github.com/rescript-lang/rescript-compiler/pull/6893
- Remove `@uncurry` from ReScript sources (others, tests). https://github.com/rescript-lang/rescript-compiler/pull/6938
- Remove leftover uncurried handling. https://github.com/rescript-lang/rescript-compiler/pull/6939 https://github.com/rescript-lang/rescript-compiler/pull/6940
- Start converting tests from mocha to the node test runner. https://github.com/rescript-lang/rescript-compiler/pull/6956

#### :nail_care: Polish

- Make the `--help` arg be prioritized in the CLI, so correctly prints help message and skip other commands. https://github.com/rescript-lang/rescript-compiler/pull/6667
- Remove redundant space for empty return in generated js code. https://github.com/rescript-lang/rescript-compiler/pull/6745
- Remove redundant space for export in generated js code. https://github.com/rescript-lang/rescript-compiler/pull/6560
- Remove redundant space after continue in generated js code. https://github.com/rescript-lang/rescript-compiler/pull/6743
- Remove empty export blocks in generated js code. https://github.com/rescript-lang/rescript-compiler/pull/6744
- Fix indent for returned/thrown/wrapped in parentheses objects in generated js code. https://github.com/rescript-lang/rescript-compiler/pull/6746
- Fix indent in generated js code. https://github.com/rescript-lang/rescript-compiler/pull/6747
- In generated code, use `let` instead of `var`. https://github.com/rescript-lang/rescript-compiler/pull/6102
- Turn off transformation for closures inside loops when capturing loop variables, now that `let` is emitted instead of `var`. https://github.com/rescript-lang/rescript-compiler/pull/6480
- Improve unused attribute warning message. https://github.com/rescript-lang/rescript-compiler/pull/6787
- Remove internal option `use-stdlib` from build schema. https://github.com/rescript-lang/rescript-compiler/pull/6778
- Fix `Js.Types.JSBigInt` payload to use native `bigint` type. https://github.com/rescript-lang/rescript-compiler/pull/6911
- Deprecate `%external` extension, which has never been officially introduced. https://github.com/rescript-lang/rescript-compiler/pull/6906
- Deprecate `xxxU` functions in Belt. https://github.com/rescript-lang/rescript-compiler/pull/6941
- Improve error messages for function arity errors. https://github.com/rescript-lang/rescript-compiler/pull/6990
- Add missing HTML attribute capture to JsxDOM.res. https://github.com/rescript-lang/rescript-compiler/pull/7006

# 11.1.3

#### :bug: Bug Fix

- Fix tag function location on compiler error. https://github.com/rescript-lang/rescript-compiler/pull/6816
- Fix Deno compatibility issues on Windows. https://github.com/rescript-lang/rescript-compiler/pull/6850
- Fix issue with infinite loops with type errors on recursive types. https://github.com/rescript-lang/rescript-compiler/pull/6867
- Ignore `@uncurry` attribute in uncurried mode, to avoid generating calls to `Curry` at runtime. https://github.com/rescript-lang/rescript-compiler/pull/6869
- Avoid generating calls to Curry when adjusting arity of uncurried functions. https://github.com/rescript-lang/rescript-compiler/pull/6870
- Fix build after calling without `-warn-error`, see https://github.com/rescript-lang/rescript-compiler/issues/6868 for more details. https://github.com/rescript-lang/rescript-compiler/pull/6877
- Fix issue with uninitialized `_param` in recursive functions with unit argument. https://github.com/rescript-lang/rescript-compiler/pull/6907

# 11.1.3-rc.1

#### :bug: Bug Fix

- Omit standard library dir from load path if -nostdlib is set. https://github.com/rescript-lang/rescript-compiler/pull/6833

# 11.1.2

#### :bug: Bug Fix

- Fix issue where capitalised type variables were only allowed in certain positions. https://github.com/rescript-lang/rescript-compiler/pull/6820

# 11.1.2-rc.1

#### :rocket: New Feature

- Support Windows 11 ARM (using the x64 binaries in emulation). https://github.com/rescript-lang/rescript-compiler/pull/6813

#### :bug: Bug Fix

- Fix location of let bindings with attributes. https://github.com/rescript-lang/rescript-compiler/pull/6791
- PPX v4: mark props type in externals as `@live` to avoid dead code warnings for prop fields in the editor tooling. https://github.com/rescript-lang/rescript-compiler/pull/6796
- Fix issue where optional labels were not taken into account when disambiguating record value construction. https://github.com/rescript-lang/rescript-compiler/pull/6798
- Fix issue in gentype when type `Jsx.element` surfaces to the user. https://github.com/rescript-lang/rescript-compiler/pull/6808
- Fix inclusion check (impl vs interface) for untagged variants, and fix the outcome printer to show tags. https://github.com/rescript-lang/rescript-compiler/pull/6669
- Fix encoding inside tagged template literals. https://github.com/rescript-lang/rescript-compiler/pull/6810

# 11.1.1

#### :bug: Bug Fix

- Fix issue of incorrect switch cases with identical bodies when mixing object and array. https://github.com/rescript-lang/rescript-compiler/pull/6792
- Fix formatter eats comments on the first argument of a uncurried function. https://github.com/rescript-lang/rescript-compiler/pull/6763
- Fix formatter removes parens in pipe operator with anonymous uncurried function. https://github.com/rescript-lang/rescript-compiler/pull/6766

# 11.1.0

#### :bug: Bug Fix

- Revert escape JSX prop names with hyphens (#6705). https://github.com/rescript-lang/rescript-compiler/pull/6731

# 11.1.0-rc.8

#### :rocket: New Feature

- Add `%todo` extension for leaving implementation for later. https://github.com/rescript-lang/rescript-compiler/pull/6713
- Add `-warn-error` argument for generating errors in CI. Useful for `%todo` extension. https://github.com/rescript-lang/rescript-compiler/pull/6717

#### :bug: Bug Fix

- Improve error when using `@deriving(accessors)` on a variant with record arguments. https://github.com/rescript-lang/rescript-compiler/pull/6712
- Stop escaping JSX prop names with hyphens. https://github.com/rescript-lang/rescript-compiler/pull/6705
- Fix trailing undefined for optional parameters not omitted with `@send` and `@new`. https://github.com/rescript-lang/rescript-compiler/pull/6716
- Fix JSX4 adding the incorrect type annotation for the prop `ref` in `React.forwardRef` component. https://github.com/rescript-lang/rescript-compiler/pull/6718
- Fix description for warning number 110. https://github.com/rescript-lang/rescript-compiler/pull/6725

#### :nail_care: Polish

- Module spec `es6` and `es6-global` is deprecated in favor of `esmodule`. https://github.com/rescript-lang/rescript-compiler/pull/6709

# 11.1.0-rc.7

#### :bug: Bug Fix

- Fix variance setting for builtin `dict` type. Fixes issues around inference. https://github.com/rescript-lang/rescript-compiler/pull/6707

# 11.1.0-rc.6

#### :rocket: New Feature

- Add experimental BigInt support. https://github.com/rescript-lang/rescript-compiler/pull/6670, https://github.com/rescript-lang/rescript-compiler/pull/6696

#### :bug: Bug Fix

- Fix mishandling of uncurried functions in super errors. https://github.com/rescript-lang/rescript-compiler/pull/6694

# 11.1.0-rc.5

#### :bug: Bug Fix

- Fix misparsing in/after JSX. https://github.com/rescript-lang/rescript-compiler/pull/6686
- Fix `@deriving(accessors)` outputting curried functions in uncurried mode. https://github.com/rescript-lang/rescript-compiler/pull/6687

# 11.1.0-rc.4

#### :bug: Bug Fix

- Fix emitting static import instead of dynamic import. https://github.com/rescript-lang/rescript-compiler/pull/6664
- Fix local type variables breaking react components. https://github.com/rescript-lang/rescript-compiler/pull/6665
- Fix remove redundant branches in generated switch body. https://github.com/rescript-lang/rescript-compiler/pull/6672
- Fix issue in partial application when the last named arg is provided. https://github.com/rescript-lang/rescript-compiler/pull/6681

#### :nail-care: Polish

- Omit `undefined` in external function calls for trailing optional arguments when not supplied. https://github.com/rescript-lang/rescript-compiler/pull/6653
- Make pattern match suggestions to be easier to copy-paste. https://github.com/rescript-lang/rescript-compiler/pull/6656

# 11.1.0-rc.3

#### :nail_care: Polish

- No parens around tagged template literals. https://github.com/rescript-lang/rescript-compiler/pull/6639
- Allow identifier with modules in tagged template literals (e.g. Pg.sql`select * from ${table} where id = ${id}`). https://github.com/rescript-lang/rescript-compiler/pull/6645

#### :bug: Bug Fix

- Fix compiler crash when reexporting tagged template literal externals. https://github.com/rescript-lang/rescript-compiler/pull/6645

# 11.1.0-rc.2

#### :rocket: New Feature

- Add support for array spread. https://github.com/rescript-lang/rescript-compiler/pull/6608
- Support import attributes (https://github.com/tc39/proposal-import-attributes) in `@module()`. https://github.com/rescript-lang/rescript-compiler/pull/6599
- allow hyphens in jsx tag names (e.g. `<mj-column>`). https://github.com/rescript-lang/rescript-compiler/pull/6609

#### :bug: Bug Fix

- Fix issue with async and newtype in uncurried mode. https://github.com/rescript-lang/rescript-compiler/pull/6601
- Generic JSX transform: Rename expected module name for lowercase JSX to `Elements` from `DOM`. https://github.com/rescript-lang/rescript-compiler/pull/6606
- Generic JSX transform: Set default config params for `jsxConfig`. https://github.com/rescript-lang/rescript-compiler/pull/6606
- Generic JSX transform: Handle namespaced names. https://github.com/rescript-lang/rescript-compiler/pull/6606
- Fix issue with doc comment in recursive module. https://github.com/rescript-lang/rescript-compiler/pull/6613
- Fix issue with Exceptions and Extensible types runtime generation. https://github.com/rescript-lang/rescript-compiler/pull/6570
- Fix inline comment before spread syntax in record. https://github.com/rescript-lang/rescript-compiler/pull/6615

#### :house: Internal

- Use OCaml 4.14.1 (+ Alpine 3.19 container) for CI build. https://github.com/rescript-lang/rescript-compiler/pull/6600

# 11.1.0-rc.1

#### :rocket: New Feature

- Experimental support of tagged template literals, e.g. `` sql`select * from ${table}` ``. https://github.com/rescript-lang/rescript-compiler/pull/6250
- Experimental support for generic/custom JSX transforms. https://github.com/rescript-lang/rescript-compiler/pull/6565
- `dict` is now a builtin type. https://github.com/rescript-lang/rescript-compiler/pull/6590

#### :bug: Bug Fix

- GenType: distinguish inline records from unary variant cases of object type. https://github.com/rescript-lang/rescript-compiler/pull/6586

# 11.0.1

#### :bug: Bug Fix

- Renamed inline record fields: fix renamed field access in inline records. https://github.com/rescript-lang/rescript-compiler/pull/6551
- Fixed issue with coercions sometimes raising a `Not_found` instead of giving a proper error message. https://github.com/rescript-lang/rescript-compiler/pull/6574
- Fix issue with recursive modules and uncurried. https://github.com/rescript-lang/rescript-compiler/pull/6575

#### :nail_care: Polish

- Improve error message for missing label(s) in function application. https://github.com/rescript-lang/rescript-compiler/pull/6576

# 11.0.0

No changes compared to rc.9.

# 11.0.0-rc.9

#### :rocket: New Feature

- GenType: support `@deriving(accessors)` outputs. https://github.com/rescript-lang/rescript-compiler/pull/6537
- Allow coercing ints and floats to unboxed variants that have a catch-all unboxed int or float case. https://github.com/rescript-lang/rescript-compiler/pull/6540
- Allow tuples in untagged variants. https://github.com/rescript-lang/rescript-compiler/pull/6550

#### :bug: Bug Fix

- GenType: now emits full suffix on JS import path to be compatible with `.res.js`. https://github.com/rescript-lang/rescript-compiler/pull/6541

#### :nail_care: Polish

- Format docstrings. https://github.com/rescript-lang/rescript-compiler/pull/6417
- JSX v4: make automatic mode the default. https://github.com/rescript-lang/rescript-compiler/pull/6552

# 11.0.0-rc.8

#### :rocket: New Feature

- Add support for type coercion for invariant type arguments such as array payloads. https://github.com/rescript-lang/rescript-compiler/pull/6518
- Start treating `rescript` command the same as the `rescript build` command, so now you can do `rescript -w`. https://github.com/rescript-lang/rescript-compiler/pull/6524

#### :bug: Bug Fix

- Fix accidental removal of `Belt.Result.Ok` and `Belt.Result.Error` constructors in rc.5. https://github.com/rescript-lang/rescript-compiler/pull/6514
- Add missing check that the runtime representation of variants matches implementation and interface. https://github.com/rescript-lang/rescript-compiler/pull/6513/files
- GenType: only export types (not values) from module types. https://github.com/rescript-lang/rescript-compiler/pull/6516
- Fix compiler crash with unboxed variant definition with only 1 constructor. https://github.com/rescript-lang/rescript-compiler/pull/6523
- GenType: support mutual recursive types inside modules. https://github.com/rescript-lang/rescript-compiler/pull/6528
- Workaround for `@as` in labels in uncurried externals, which was broken. https://github.com/rescript-lang/rescript-compiler/pull/6527

#### :nail_care: Polish

- GenType: make outputs DCE-friendly. https://github.com/rescript-lang/rescript-compiler/pull/6508

# 11.0.0-rc.7

#### :rocket: New Feature

- Allow empty inline records in variants. https://github.com/rescript-lang/rescript-compiler/pull/6494
- Allow empty record patterns in pattern matching. https://github.com/rescript-lang/rescript-compiler/pull/6494

#### :bug: Bug Fix

- Fix issue where an inline record with attributes did not parse. https://github.com/rescript-lang/rescript-compiler/pull/6499
- Fix issue with uncurried function with 1 arg being a variable where an undefined variable could be emitted. https://github.com/rescript-lang/rescript-compiler/pull/6507
- Fix runtime errors on `@genType.as("alias")` output. https://github.com/rescript-lang/rescript-compiler/pull/6509

# 11.0.0-rc.6

#### :rocket: New Feature

- Freely configurable suffix for generated .js files. https://github.com/rescript-lang/rescript-compiler/pull/6472

#### :bug: Bug Fix

- Fix issue with GenType and `result` introduced in rc.5. https://github.com/rescript-lang/rescript-compiler/pull/6464
- Fix compiler crash when inlining complex constants in pattern matching. https://github.com/rescript-lang/rescript-compiler/pull/6471
- Fix issue with generating async functions inside loops. https://github.com/rescript-lang/rescript-compiler/pull/6479
- Fix issue with Gentype and string annotations with numbers such as `@as("0")`. https://github.com/rescript-lang/rescript-compiler/pull/6487
- Fix error message on curried/uncurried signature mismatch. https://github.com/rescript-lang/rescript-compiler/pull/6414

#### :nail_care: Polish

- Improve some error messages in rescript.conf parsing. https://github.com/rescript-lang/rescript-compiler/pull/6469

# 11.0.0-rc.5

#### :rocket: New Feature

- Allow coercing unboxed variants with only strings (now including with a single payload of string) to the primitive string. https://github.com/rescript-lang/rescript-compiler/pull/6441
- Allow coercing strings to unboxed variants that have a catch-all unboxed string case. https://github.com/rescript-lang/rescript-compiler/pull/6443
- Allow coercing `int` to `float`. https://github.com/rescript-lang/rescript-compiler/pull/6448

#### :bug: Bug Fix

- Fix issue with dynamic import of module in nested expressions. https://github.com/rescript-lang/rescript-compiler/pull/6431
- Fix issue where GenType was not supporting `@tag` on ordinary variants. https://github.com/rescript-lang/rescript-compiler/pull/6437
- Fix using dynamic import of module in block instead of async function. https://github.com/rescript-lang/rescript-compiler/pull/6434
- Fix issue with using dynamic import of module in uncurried mode. https://github.com/rescript-lang/rescript-compiler/pull/6434
- Fix build error with JSX v4 transformation of React.forwardRef in uncurried mode. https://github.com/rescript-lang/rescript-compiler/pull/6447
- Fix printing of exotic JSX names. https://github.com/rescript-lang/rescript-compiler/pull/6451
- Fix locations when code with `await` fails to compile (all locations would point to the internal function `unsafe_await`). https://github.com/rescript-lang/rescript-compiler/pull/6452
- Fix renaming fields (with @as) in inline records doesn't work when destructuring. https://github.com/rescript-lang/rescript-compiler/pull/6456
- Fix `rc.4` regressions:
  - Don't show compilation time when calling `rescript build -help` command. https://github.com/rescript-lang/rescript-compiler/pull/6439
  - Running `rescript build -w` with a compilation error doesn't exit with an error code and continues waiting for changes. https://github.com/rescript-lang/rescript-compiler/pull/6460

#### :house: Internal

- Remove dependency stdlib-406 -> belt. https://github.com/rescript-lang/rescript-compiler/pull/6453
- Playground: Add support for implicitly opened modules. https://github.com/rescript-lang/rescript-compiler/pull/6446

#### :nail_care: Polish

- Add [`Deno`](https://deno.land/api?s=Deno) to reserved names, so that modules named `Deno` don't clash with the globally exposed `Deno` object. https://github.com/rescript-lang/rescript-compiler/pull/6428
- Disable ESLint/TSLint on gentype outputs properly. https://github.com/rescript-lang/rescript-compiler/pull/6442
- Improve `rescript` CLI to use `stdout`/`stderr` appropriately for help command's message. https://github.com/rescript-lang/rescript-compiler/pull/6439
- Generate `f()` instead of `f(undefined)` for `f()`. https://github.com/rescript-lang/rescript-compiler/pull/6459

# 11.0.0-rc.4

#### :rocket: New Feature

- Support renaming fields in inline records with `@as` attribute. [#6391](https://github.com/rescript-lang/rescript-compiler/pull/6391)
- Support renaming object fields of `@obj` external ppx with `@as` attribute. [#6391](https://github.com/rescript-lang/rescript-compiler/pull/6412)
- Add builtin abstract types for File and Blob APIs. https://github.com/rescript-lang/rescript-compiler/pull/6383
- Untagged variants: Support `promise`, RegExes, Dates, File and Blob. https://github.com/rescript-lang/rescript-compiler/pull/6383
- Untagged variants: Support `bool`. https://github.com/rescript-lang/rescript-compiler/pull/6368
- Support aliased types as payloads to untagged variants. https://github.com/rescript-lang/rescript-compiler/pull/6394
- Support the async component for React Server Component in JSX V4. https://github.com/rescript-lang/rescript-compiler/pull/6399
- Support `rescript.json` configuration file and deprecate `bsconfig.json`. https://github.com/rescript-lang/rescript-compiler/pull/6382

#### :boom: Breaking Change

- Update watcher rules to recompile only on config and `*.res`/`*.resi`/`*.ml`/`.mli` file changes. Solves the issue of unnecessary recompiles on `.css`, `.ts`, and other unrelated file changes. https://github.com/rescript-lang/rescript-compiler/pull/6420
- Add smart printer for pipe chains. https://github.com/rescript-lang/rescript-compiler/pull/6411 (the formatter will reformat existing code in certain cases)
- `Js.Json.t` now uses `Boolean(bool)` instead of explicit `@as(true) True | @as(false) False`. https://github.com/rescript-lang/rescript-compiler/pull/6421

#### :bug: Bug Fix

- Fix issue with GenType and labelled arguments. https://github.com/rescript-lang/rescript-compiler/pull/6406
- Fix dependencies reinitialization on every change in watch mode. Leads to faster rebuilds and cleaner terminal. https://github.com/rescript-lang/rescript-compiler/pull/6404

#### :nail_care: Polish

- A little performance improvement for JSX V4 runtime helper by removing one object allocation for components with key prop. https://github.com/rescript-lang/rescript-compiler/pull/6376
- The error message for "toplevel expressions should evaluate to unit" has been revamped and improved. https://github.com/rescript-lang/rescript-compiler/pull/6407
- Improve "Somewhere wanted" error messages by changing wording and adding more context + suggested solutions to the error messages where appropriate. https://github.com/rescript-lang/rescript-compiler/pull/6410
- Display the compile time for `rescript build` command. https://github.com/rescript-lang/rescript-compiler/pull/6404
- Improve help message for `build` and `clean` commands. https://github.com/rescript-lang/rescript-compiler/pull/6404
- Pass through the `-verbose` flag to builds in watch mode. https://github.com/rescript-lang/rescript-compiler/pull/6404
- Improve error message when defining duplicate labels in a record. https://github.com/rescript-lang/rescript-compiler/pull/6415
- Improve error message when trying to concatenate strings using the wrong operator. https://github.com/rescript-lang/rescript-compiler/pull/6416

# 11.0.0-rc.3

#### :bug: Bug Fix

- Fix issue with JSX V4 when component props have the default value with same name. https://github.com/rescript-lang/rescript-compiler/pull/6377
- Fixed code formatter with `"uncurried": false` in bsconfig. https://github.com/rescript-lang/rescript-compiler/pull/6378

#### :nail_care: Polish

- Add [`Bun`](https://bun.sh) to reserved names, so that modules named `Bun` don't clash with the globally exposed `Bun` object. https://github.com/rescript-lang/rescript-compiler/pull/6381

# 11.0.0-rc.2

#### :rocket: New Feature

- `rescript build` will always build its dependency by default. The argument `-with-deps` is not needed anymore. https://github.com/rescript-lang/rescript-compiler/pull/6350

#### :boom: Breaking Change

- Stop mangling object field names. If you had objects with field names containing "\_\_" or leading "\_", they won't be mangled in the compiled JavaScript and represented as it is without changes. https://github.com/rescript-lang/rescript-compiler/pull/6354

#### :bug: Bug Fix

- Fixed outcome printer resolution of uncurried config. https://github.com/rescript-lang/rescript-compiler/pull/6353

# 11.0.0-rc.1

#### :rocket: New Feature

- GenType: Propagate comments from record fields to emitted TypeScript types. https://github.com/rescript-lang/rescript-compiler/pull/6333

#### :boom: Breaking Change

- `$$default` is no longer exported from the generated JavaScript when using default exports. https://github.com/rescript-lang/rescript-compiler/pull/6328

#### :nail_care: Polish

- Conditionally print error message about record with missing label potentially being a component. https://github.com/rescript-lang/rescript-compiler/pull/6337
- Put definition in the bottom and the actual error at the top when reporting errors for supplying fields etc with the wrong name. https://github.com/rescript-lang/rescript-compiler/pull/6336
- Fix left over places where polyvariant tag names were printed in OCaml syntax instead of ReScript. https://github.com/rescript-lang/rescript-compiler/pull/6348

# 11.0.0-beta.4

#### :rocket: New Feature

- Variants: Allow coercing from variant to variant where applicable. https://github.com/rescript-lang/rescript-compiler/pull/6314
- Variants: Experimental support for spreading variant type definitions to copy constructors from one variant to another. https://github.com/rescript-lang/rescript-compiler/pull/6316

#### :boom: Breaking Change

- Fixed name collision between the newly defined Js.Json.t and the variant constructor in the existing Js.Json.kind type. To address this, the usage of the existing Js.Json.kind type can be updated to Js.Json.Kind.t. https://github.com/rescript-lang/rescript-compiler/pull/6317

#### :bug: Bug Fix

- Fixed outcome printing of uncurried higher order function types. https://github.com/rescript-lang/rescript-compiler/pull/6323
- Fixed printing of type constraints in template literal substitutions. https://github.com/rescript-lang/rescript-compiler/pull/6324

# 11.0.0-beta.3

#### :rocket: New Feature

- Untagged variants: consider regexp as an object type. https://github.com/rescript-lang/rescript-compiler/pull/6296
- Semantic-based optimization of code generated for untagged variants. https://github.com/rescript-lang/rescript-compiler/issues/6108
- Record type spreads: Allow using type variables in type spreads. Both uninstantiated and instantiated ones. https://github.com/rescript-lang/rescript-compiler/pull/6309
- Variants: Allow coercing variants to string/int/float when applicable. https://github.com/rescript-lang/rescript-compiler/pull/6311

#### :bug: Bug Fix

- Fix issue with dynamic import of modules in expressions. https://github.com/rescript-lang/rescript-compiler/pull/6310

# 11.0.0-beta.2

#### :rocket: New Feature

- Introduced a new `%ffi` extension (_experimental_ - not for production use!) that provides a more robust mechanism for JavaScript function interoperation by considering function arity in type constraints. This enhancement improves safety when dealing with JavaScript functions by enforcing type constraints based on the arity of the function. https://github.com/rescript-lang/rescript-compiler/pull/6251
- Extended untagged variants with function types. https://github.com/rescript-lang/rescript-compiler/pull/6279

#### :boom: Breaking Change

- Remove rudimentary node bindings and undocumented `%node` extension. https://github.com/rescript-lang/rescript-compiler/pull/6285

#### :bug: Bug Fix

- Fix issue where uncurried type internals leak in type error. https://github.com/rescript-lang/rescript-compiler/pull/6264
- Improve error messages for untagged variant definition. https://github.com/rescript-lang/rescript-compiler/pull/6290
- Fix type checking performance issue for large records. https://github.com/rescript-lang/rescript-compiler/pull/6289

# 11.0.0-beta.1

#### :rocket: Main New Feature

- Make uncurried mode opt-out: by default, every project is now in uncurried mode, unless `"uncurried": false` is specified in the project config. https://github.com/rescript-lang/rescript-compiler/pull/6249

#### :nail_care: Polish

- Removed duplicate Super_error implementation in syntax. https://github.com/rescript-lang/rescript-compiler/pull/6246

#### :bug: Bug Fix

- Fix issue with inlining records in the presence of record coercion. https://github.com/rescript-lang/rescript-compiler/pull/6256

# 11.0.0-alpha.6

#### :boom: Breaking Change

- `-bs-super-errors` flag has been deprecated along with Super_errors. https://github.com/rescript-lang/rescript-compiler/pull/6243
- `@rescript/react` >= 0.12.0-alpha.2 is now required because of the React.fragment's children type fix. https://github.com/rescript-lang/rescript-compiler/pull/6238

#### :bug: Bug Fix

- Remove unnecessary require and import statements when using dynamic imports. https://github.com/rescript-lang/rescript-compiler/pull/6232
- Fix option unboxing logic in the presence of untagged variants. https://github.com/rescript-lang/rescript-compiler/pull/6233
- Fix printing of local module with type. https://github.com/rescript-lang/rescript-compiler/issues/6212
- Adapting JSX4 to React.fragment's children type change (`'children` -> `React.element`) https://github.com/rescript-lang/rescript-compiler/pull/6238

#### :nail_care: Polish

- In uncurried mode, outcome printer swaps curried and uncurries function printing compared to legacy.
- Add location information to duplicate type definition error messages. https://github.com/rescript-lang/rescript-compiler/pull/6199
- Replace normal module errors with Super_error module, and clean up Super_error. https://github.com/rescript-lang/rescript-compiler/pull/6199
- `Js.Json.t`, `Js.null` and `Js.nullable` are now untagged variants representing their runtime values, instead of abstract types. https://github.com/rescript-lang/rescript-compiler/pull/6218

# 11.0.0-alpha.5

#### :rocket: Main New Feature

- Add support for Dynamic import. https://github.com/rescript-lang/rescript-compiler/pull/5703
- GenType: Add `moduleResolution` option to customize extensions on emitted import statements. This helps to adjust output compatibility with TypeScript projects using ESM. https://github.com/rescript-lang/rescript-compiler/pull/6182
  - `node` (default): Drop extensions.
  - `node16`: Use TS output's extensions. Make it ESM-compatible.
  - `bundler`: Use TS input's extensions. Make it ESM-compatible.
- Make untagged variants understand payloads defined as records. https://github.com/rescript-lang/rescript-compiler/pull/6208

#### :boom: Breaking Change

- Parse `assert` as a regular function. `assert` is no longer a unary expression. Example: before `assert 1 == 2` is parsed as `(assert 1) == 2`, now it is parsed as `assert(1 == 2)`. https://github.com/rescript-lang/rescript-compiler/pull/6180

#### :bug: Bug Fix

- Make "rescript format" work with node 10 again and set minimum required node version to 10 in package.json. https://github.com/rescript-lang/rescript-compiler/pull/6186
- Fix partial application for uncurried functions with labeled args https://github.com/rescript-lang/rescript-compiler/pull/6198
- Add error messages for dangling doc comments/attributes and mutable in record type definition. https://github.com/rescript-lang/rescript-compiler/pull/6206
- Fix issue with overlapping array and object in untagged variants https://github.com/rescript-lang/rescript-compiler/pull/6219

# 11.0.0-alpha.4

#### :rocket: Main New Feature

- Add surface syntax for partial application of uncurried functions: `foo(1, ...)`. This corresponds to curried application in the old mode. https://github.com/rescript-lang/rescript-compiler/pull/6166

#### :bug: Bug Fix

- Fix broken formatting in uncurried mode for functions with \_ placeholder args. https://github.com/rescript-lang/rescript-compiler/pull/6148
- Fix issue where spreading record types with optional labels would not have their labels preserved as optional. https://github.com/rescript-lang/rescript-compiler/pull/6154
- Fix error location to be the type with the spreads when spreading record types with duplicate labels. https://github.com/rescript-lang/rescript-compiler/pull/6157
- Disable warning on `@inline` attibute on uncurried functions. https://github.com/rescript-lang/rescript-compiler/pull/6152
- Support doc comments on arguments of function types. https://github.com/rescript-lang/rescript-compiler/pull/6161
- Fix issue with record type coercion and unboxed. https://github.com/rescript-lang/rescript-compiler/issues/6158
- Fixed subtype checking for record types with "@as" attributes: The subtype relationship now takes into account the compatibility of "@as" attributes between corresponding fields, ensuring correctness in runtime representation.
  https://github.com/rescript-lang/rescript-compiler/issues/6158
- Emit directive above header comment. https://github.com/rescript-lang/rescript-compiler/pull/6172
- Add error message to private extension. https://github.com/rescript-lang/rescript-compiler/pull/6175

#### :nail_care: Polish

- Update list of reserved JS keywords. https://github.com/rescript-lang/rescript-compiler/pull/6167
- Add error message to `@@directive`. https://github.com/rescript-lang/rescript-compiler/pull/6174

# 11.0.0-alpha.3

#### :rocket: Main New Feature

- Add support for extensible records (e.g. `type t = {...t1, x:int, ...t2}`) https://github.com/rescript-lang/rescript-compiler/pull/5715

#### :bug: Bug Fix

- Fix formatting and parentheses placement in uncurried functions with constraints. https://github.com/rescript-lang/rescript-compiler/pull/6143

# 11.0.0-alpha.2

#### :rocket: Main New Feature

- Add support for type coercion `:>` for records. https://github.com/rescript-lang/rescript-compiler/pull/5721

#### :bug: Bug Fix

- Special case generation of uncurried functions with 1 argument of unit type so they don't take a parameter. https://github.com/rescript-lang/rescript-compiler/pull/6131

# 11.0.0-alpha.1

#### :rocket: Main New Feature

- Introduce experimental uncurried mode. For experimentation only. [PR #5796](https://github.com/rescript-lang/rescript-compiler/pull/5796)
- Customization of runtime representation of variants and introduction of untagged variants [PR #6095](https://github.com/rescript-lang/rescript-compiler/pull/6095), [PR #6103](https://github.com/rescript-lang/rescript-compiler/pull/6103)

#### :rocket: New Feature

- Add support for uncurried mode: a mode where everything is considered uncurried, whether with or without the `.`. This can be turned on with `@@uncurried` locally in a file. For project-level configuration in `bsconfig.json`, there's a boolean config `"uncurried"`, which propagates to dependencies, to turn on uncurried mode.
  Since there's no syntax for partial application in this new mode, introduce `@res.partial foo(x)` to express partial application. This is temporary and will later have some surface syntax.
  Make uncurried functions a subtype of curried functions, and allow application for uncurried functions.
  The `make` function of components is generated as an uncurried function.
  Use best effort to determine the config when formatting a file.
  https://github.com/rescript-lang/rescript-compiler/pull/5968 https://github.com/rescript-lang/rescript-compiler/pull/6080 https://github.com/rescript-lang/rescript-compiler/pull/6086 https://github.com/rescript-lang/rescript-compiler/pull/6087
- Customization of runtime representation of variants. This is work in progress. E.g. some restrictions on the input. See comments of the form "TODO: put restriction on the variant definitions allowed, to make sure this never happens". https://github.com/rescript-lang/rescript-compiler/pull/6095
- Introduce untagged variants https://github.com/rescript-lang/rescript-compiler/pull/6103
- Add support for unary uncurried pipe in uncurried mode https://github.com/rescript-lang/rescript-compiler/pull/5804
- Add support for partial application of uncurried functions: with uncurried application one can provide a
  subset of the arguments, and return a curried type with the remaining ones https://github.com/rescript-lang/rescript-compiler/pull/5805
- Add support for uncurried externals https://github.com/rescript-lang/rescript-compiler/pull/5815 https://github.com/rescript-lang/rescript-compiler/pull/5819 https://github.com/rescript-lang/rescript-compiler/pull/5830 https://github.com/rescript-lang/rescript-compiler/pull/5894
- Parser/Printer: unify uncurried functions of arity 0, and of arity 1 taking unit. There's now only arity 1 in the source language. https://github.com/rescript-lang/rescript-compiler/pull/5825
- Add support for default arguments in uncurried functions https://github.com/rescript-lang/rescript-compiler/pull/5835
- Inline uncurried application when it is safe https://github.com/rescript-lang/rescript-compiler/pull/5847
- Support optional named arguments without a final unit in uncurried functions https://github.com/rescript-lang/rescript-compiler/pull/5907
- GenType: add the option to use the `@genType` annotation at the module level, meaning that all the items in the module should be exported. https://github.com/rescript-lang/rescript-compiler/pull/6113
- GenType: add support for `@genType` annotations on module definitions. https://github.com/rescript-lang/rescript-compiler/pull/6113
- Prebuilt binaries are now provided for all major platforms:
  - macOS x64
  - macOS ARM
  - Linux x64 (statically linked)
  - Linux ARM (statically linked)
  - Windows x64

#### :boom: Breaking Change

- Remove support for the legacy Reason syntax. Existing Reason code can be converted to ReScript syntax using ReScript 9 as follows:
  - `npm i -g rescript@9`
  - `rescript convert <reason files>`
- Remove obsolete built-in project templates and the "rescript init" functionality. This is replaced by [create-rescript-app](https://github.com/rescript-lang/create-rescript-app) which is maintained separately.
- Do not attempt to build ReScript from source on npm postinstall for platforms without prebuilt binaries anymore.
- Made pinned dependencies transitive: if _a_ is a pinned dependency of _b_ and _b_ is a pinned dependency of _c_, then _a_ is implicitly a pinned dependency of _c_. This change is only breaking if your build process assumes non-transitivity.
- Curried after uncurried is not fused anymore: `(. x) => y => 3` is not equivalent to `(. x, y) => 3` anymore. It's instead equivalent to `(. x) => { y => 3 }`.
  Also, `(. int) => string => bool` is not equivalen to `(. int, string) => bool` anymore.
  These are only breaking changes for unformatted code.
- Exponentiation operator `**` is now right-associative. `2. ** 3. ** 2.` now compile to `Math.pow(2, Math.pow(3, 2))` and not anymore `Math.pow(Math.pow(2, 3), 2)`. Parentheses can be used to change precedence.
- Remove unsafe `` j`$(a)$(b)` `` interpolation deprecated in compiler version 10 https://github.com/rescript-lang/rescript-compiler/pull/6068
- Remove deprecated module `Printexc`
- `@deriving(jsConverter)` not supported anymore for variant types https://github.com/rescript-lang/rescript-compiler/pull/6088
- New representation for variants, where the tag is a string instead of a number. https://github.com/rescript-lang/rescript-compiler/pull/6088
- GenType: removed support for `@genType.as` for records and variants which has become unnecessary. Use the language's `@as` instead to channge the runtime representation without requiring any runtime conversion during FFI. https://github.com/rescript-lang/rescript-compiler/pull/6099 https://github.com/rescript-lang/rescript-compiler/pull/6101

#### :bug: Bug Fix

- Fix issue where uncurried was not supported with pipe https://github.com/rescript-lang/rescript-compiler/pull/5803
- Fix printing of nested types in uncurried mode https://github.com/rescript-lang/rescript-compiler/pull/5826
- Fix issue in printing uncurried callbacks https://github.com/rescript-lang/rescript-compiler/pull/5828
- Fix formatting uncurried functions with attributes https://github.com/rescript-lang/rescript-compiler/pull/5829
- Fix parsing/printing uncurried functions with type parameters https://github.com/rescript-lang/rescript-compiler/pull/5849
- Fix compiler ppx issue when combining `async` and uncurried application https://github.com/rescript-lang/rescript-compiler/pull/5856
- Fix issue where the internal representation of uncurried types would leak when a non-function is applied in a curried way https://github.com/rescript-lang/rescript-compiler/pull/5892
- Fix some comments disappearing in array access expressions https://github.com/rescript-lang/rescript-compiler/pull/5947
- Parser: fix location of variable when function definition `{v => ...}` is enclosed in braces https://github.com/rescript-lang/rescript-compiler/pull/5949
- Fix issue with error messages for uncurried functions where expected and given type were swapped https://github.com/rescript-lang/rescript-compiler/pull/5973
- Fix issue with integer overflow check https://github.com/rescript-lang/rescript-compiler/pull/6028
- Make internal encoding of locations aware of unicode https://github.com/rescript-lang/rescript-compiler/pull/6073
- Fix issue where `foo(x,_)` in uncurried mode would generate a curried function https://github.com/rescript-lang/rescript-compiler/pull/6082
- Fix printing of uncurried application when the lhs is a function definition https://github.com/rescript-lang/rescript-compiler/pull/6084
- Fix parsing uncurried type starting with path https://github.com/rescript-lang/rescript-compiler/pull/6089
- Fix bigInt comparison https://github.com/rescript-lang/rescript-compiler/pull/6097
- Fixed a bug where the async attribute was not preserved when using the `@this` decorator in ReScript functions. This fix allows proper handling of async functions with the `@this` decorator. Issue: https://github.com/rescript-lang/rescript-compiler/issues/6100
- Fix issue with GenType and module aliases https://github.com/rescript-lang/rescript-compiler/issues/6112

#### :nail_care: Polish

- Syntax: process uncurried types explicitly in the parser/printer https://github.com/rescript-lang/rescript-compiler/pull/5784 https://github.com/rescript-lang/rescript-compiler/pull/5822
- Syntax: process uncurried function declarations explicitly in the parser/printer https://github.com/rescript-lang/rescript-compiler/pull/5794
- PPX V4: allow uncurried `make` function and treat it like a curried one [#5802](https://github.com/rescript-lang/rescript-compiler/pull/5802) [#5808](https://github.com/rescript-lang/rescript-compiler/pull/5808) [#5812](https://github.com/rescript-lang/rescript-compiler/pull/5812)
- Remove processing of objects expressions, which don't exist in `.res` syntax (`Pexp_object`) https://github.com/rescript-lang/rescript-compiler/pull/5841
- Remove class type processing from compiler ppx https://github.com/rescript-lang/rescript-compiler/pull/5842
- Remove method application via operator `##`, which does not exist in `.res` syntax https://github.com/rescript-lang/rescript-compiler/pull/5844
- Treat `@meth` annotation as making the type uncurried for backwards compatibitly with some examples https://github.com/rescript-lang/rescript-compiler/pull/5845
- Process `@set` annotation for field update as generating an uncurried function https://github.com/rescript-lang/rescript-compiler/pull/5846
- Treat uncurried application of primitives like curried application, which produces better output https://github.com/rescript-lang/rescript-compiler/pull/5851
- New internal representation for uncurried functions using built-in type `function$<fun_type, arity>` this avoids having to declare all the possible arities ahead of time https://github.com/rescript-lang/rescript-compiler/pull/5870
- PPX V3: allow uncurried `make` function and treat it like a curried one https://github.com/rescript-lang/rescript-compiler/pull/6081
- Add support for `|>` in uncurried mode by desugaring it https://github.com/rescript-lang/rescript-compiler/pull/6083
- Change the compilation of pattern matching for variants so it does not depends on variats being integers https://github.com/rescript-lang/rescript-compiler/pull/6085
- Improve code generated for string templates https://github.com/rescript-lang/rescript-compiler/pull/6090
- Move Jsx and JsxDOM and JsxEvent and JsxPPXReactSupport inside Pervasives and build them separately for curried and uncurried mode https://github.com/rescript-lang/rescript-compiler/pull/6091
- Gentype: allow recursive data types https://github.com/rescript-association/genType/issues/585

# 10.1.4

#### :bug: Bug Fix

- Fix implementation of directives https://github.com/rescript-lang/rescript-compiler/pull/6052
- Fix issue if the `lib` dir is included in the sources of bsconfig.json https://github.com/rescript-lang/rescript-compiler/pull/6055
- Fix issue with string escape in pattern match https://github.com/rescript-lang/rescript-compiler/pull/6062
- Fix issue with literal comparison of string constants https://github.com/rescript-lang/rescript-compiler/pull/6065

#### :rocket: New Feature

- Add support for toplevel `await` https://github.com/rescript-lang/rescript-compiler/pull/6054

#### :nail_care: Polish

- Better error message for extension point https://github.com/rescript-lang/rescript-compiler/pull/6057
- Improve format check help https://github.com/rescript-lang/rescript-compiler/pull/6056
- Deprecate unsafe `` j`$(a)$(b)` `` interpolation: use string templates `` `${a}${b}` `` instead https://github.com/rescript-lang/rescript-compiler/pull/6067

# 10.1.3

#### :rocket: New Feature

- Add experimental suppport for directives. An annotation such as `@@directive("use client;")` emits `use client;` verbatim before imports https://github.com/rescript-lang/rescript-compiler/pull/5999
- `genType`: add `Core` standard library support for the following builtin types: `Null.t`, `Nullable.t`, `Undefined.t`, `Dict.t<_>`, `Promise.t<_>`, `Date.t`, `BigInt.t`, `RegExp.t`, `Map.t<_, _>`, `WeakMap.t<_, _>`, `Set<_>`, `WeakSet<_>` https://github.com/rescript-lang/rescript-compiler/pull/6024

#### :boom: Breaking Change

- `genType`: streamline the treatment of optionals as undefined https://github.com/rescript-lang/rescript-compiler/pull/6024
  - Represent `option<t>` as `undefined | t` instead of `null | undefined | t`. This is more permissive when importing functions taking optional values (allows to use option types), but stricter when e.g. exporting ReScript functions taking arguments of option type. Fallback: use `Js.undefined<_>` instead.
  - Represent `{x:option<string>}` as `{x:(undefined | string)}` instead of `{x?: string}`. This is more in line with TS's behaviour. Fallback: use `{x?:string}`.

#### :nail_care: Polish

- Add the gap property to jsxDOMStyle https://github.com/rescript-lang/rescript-compiler/pull/5956

#### :bug: Bug Fix

- Fix issue where error messages related to non-existent props were displayed without location information https://github.com/rescript-lang/syntax/pull/730
- Fix issue where uncurried functions were incorrectly converting the type of a prop given as a default value to curried https://github.com/rescript-lang/syntax/pull/731
- Fix issue with nested async functions, where the inner function would be emitted without `async` https://github.com/rescript-lang/rescript-compiler/pull/5984
- Fix issue with printing async functions with locally abstract types https://github.com/rescript-lang/syntax/pull/732
- Fix issue with async context and locally abstract types https://github.com/rescript-lang/rescript-compiler/pull/5985
- Fix support for recursive components in JSX V4 https://github.com/rescript-lang/syntax/pull/733
- GenType: fix issue with V3 compatibility mode (see https://github.com/rescript-lang/rescript-compiler/issues/5990) https://github.com/rescript-lang/rescript-compiler/pull/5992
- Fix issue with overlapping labelled argument with default value https://github.com/rescript-lang/syntax/pull/734
- Fix issue with using alias and default value together https://github.com/rescript-lang/syntax/pull/734
- Fix issue in `Js.Promise2` where `then` and `catch` were returning `undefined` https://github.com/rescript-lang/rescript-compiler/pull/5996
- Fix issue in the compiler back-end where async functions passed to an `@uncurry` external would be inlined and transformed in a way that loses async https://github.com/rescript-lang/rescript-compiler/pull/6011
- Fix location issue for the treatment of `async` functions where hovering on the body with a type error would show `'a => promise<'a>` everywhere https://github.com/rescript-lang/rescript-compiler/pull/6014
- Fix formatting of `switch` expressions that contain braced `cases` inside https://github.com/rescript-lang/syntax/pull/735
- Fix formatting of props spread for multiline JSX expression https://github.com/rescript-lang/syntax/pull/736
- Support `@gentype.import` as an alias to `@genType.import` in the compiler https://github.com/rescript-lang/rescript-compiler/pull/6021
- In GenType, check annotations also in module types to decide whether to produce the `.gen.tsx` file https://github.com/rescript-lang/rescript-compiler/pull/5903
- Fix issue with JSX V4 and newtype https://github.com/rescript-lang/syntax/pull/737
- Fix issue with JSX V4 when components are nested https://github.com/rescript-lang/syntax/pull/738
- Fix issue where generic compare on `float` values would be different from the compare for type `float` https://github.com/rescript-lang/rescript-compiler/pull/6043
- Improve code generated for default arguments in JSX V4 https://github.com/rescript-lang/syntax/pull/739
- Fix issue with JSX V4 props of the form `~p as module(...)` https://github.com/rescript-lang/syntax/pull/739

# 10.1.2

#### :bug: Bug Fix

- Fix an issue where error messages related to duplicate props were displayed without a loc and were unclear https://github.com/rescript-lang/syntax/pull/728

# 10.1.1

#### :boom: Breaking Change

- Parse the attributes of labelled argument to the pattern attributes of argument instead of function. https://github.com/rescript-lang/syntax/pull/722
- The prop names duplicated to keyword are not mangled automatically in JSX v4.
  - Use `@as` instead

#### :rocket: New Feature

- Add support for empty inlined record literal `{}` for inlined records where all fields are optional https://github.com/rescript-lang/rescript-compiler/pull/5900

#### :bug: Bug Fix

- Prevent inlining of async functions in additional cases https://github.com/rescript-lang/rescript-compiler/issues/5860
- Fix build error where aliasing arguments to `_` in the make function with JSX V4. https://github.com/rescript-lang/rescript-compiler/pull/5881
- Fix parsing of spread props as an expression in JSX V4 https://github.com/rescript-lang/rescript-compiler/pull/5885
- Fix dropping attributes from props in make function in JSX V4 https://github.com/rescript-lang/rescript-compiler/pull/5905

# 10.1.0

#### :bug: Bug Fix

- Fix issue where no error was reported when ? was used for non-optional fields. https://github.com/rescript-lang/rescript-compiler/pull/5853
- Fix issue where optional fields in inline records were not supported and would cause type errors https://github.com/rescript-lang/rescript-compiler/pull/5827

# 10.1.0-rc.5

#### :bug: Bug Fix

- Prevent inlining of async functions in last stage of the compiler when the functions are not exported (not in interface file or shadowed) https://github.com/rescript-lang/rescript-compiler/pull/5790

# 10.1.0-rc.4

#### :rocket: New Feature

- Support format check with `rescript format -check`. https://github.com/rescript-lang/rescript-compiler/pull/5760

#### :bug: Bug Fix

- Fix issue where the last line of `rescript format --help` usage was being swallowed https://github.com/rescript-lang/rescript-compiler/pull/5760
- Specialize the printing of the rhs of a record field assignment for optional values `{x: ? e}` https://github.com/rescript-lang/syntax/issues/714

# 10.1.0-rc.3

#### :rocket: New Feature

- Support the use of spread anywhere in list creation (e.g. `list{...x, 1, ...y, ...z}`). https://github.com/rescript-lang/syntax/pull/692
- Add support for the argument of `@react.component` to set a props type from the outside. https://github.com/rescript-lang/syntax/pull/699

#### :bug: Bug Fix

- Fix issue where the JSX key type is not an optional string https://github.com/rescript-lang/syntax/pull/693
- Prevent inlining of async functions https://github.com/rescript-lang/rescript-compiler/issues/5754
- Fix build error for JSX fragment without children https://github.com/rescript-lang/syntax/pull/704
- Fix issue where async as an id cannot be used with application and labelled arguments https://github.com/rescript-lang/syntax/issues/707
- Fix 5557: the exhaustive checking for char is incorrect during the unicode migration https://github.com/rescript-lang/rescript-compiler/pull/5749
- Fix 5753: the comment for unicode char is inaccurate https://github.com/rescript-lang/syntax/pull/709
- Treat await as almost-unary operator weaker than pipe so `await foo->bar` means `await (foo->bar)` https://github.com/rescript-lang/syntax/pull/711

#### :nail_care: Polish

- Change payload of `Pconst_char` from `char` to `int` https://github.com/rescript-lang/syntax/pull/709

# 10.1.0-rc.2

#### :bug: Bug Fix

- Fix issue with changes not being applied with React Native's Metro bundler for files with warnings https://github.com/rescript-lang/rescript-compiler/pull/5738
- Fix emitting unary minus for floats in case of negative constants https://github.com/rescript-lang/rescript-compiler/pull/5737
- Fix issue where a spread `...x` in non-last position would not be reported as syntax error https://github.com/rescript-lang/syntax/pull/673/
- Fix issue where the formatter would delete `async` in a function with labelled arguments.
- Fix several printing issues with `async` including an infinite loop https://github.com/rescript-lang/syntax/pull/680
- Fix issue where certain JSX expressions would be formatted differenctly in compiler 10.1.0-rc.1 https://github.com/rescript-lang/syntax/issues/675
- Fix issue where printing nested pipe discards await https://github.com/rescript-lang/syntax/issues/687

# 10.1.0-rc.1

#### :boom: Breaking Change

- Deprecate DOM element attributes in `JsxDOM.domProps`: `begin_`, `end_`, `to_`
  - Use `begin`, `end`, `to` instead.
- Emit an error when a `@string` or `@int` attribute is used in a V4 component https://github.com/rescript-lang/rescript-compiler/issues/5724

## :rocket: New Feature

- Add extra variants for output filename suffixes in `bsconfig.json`: `.bs.mjs` and `.bs.cjs` are allowed https://github.com/rescript-lang/rescript-compiler/pull/5631
- Safe promises: t-first Js.Promise2 bindings, and remove warning for nested promises https://github.com/rescript-lang/rescript-compiler/pull/5709

#### :bug: Bug Fix

- Fix issue where uncurried async functions were emitted without `async` https://github.com/rescript-lang/rescript-compiler/pull/5718
- Fix location issue in error messages with JSX V4 where the multiple props types are defined https://github.com/rescript-lang/syntax/pull/655
- Fix location issue in make function in JSX V4 that breaks dead code elimination https://github.com/rescript-lang/syntax/pull/660
- Fix parsing (hence pretty printing) of expressions with underscore `_` and comments.
- Fix printing of comments inside JSX tag https://github.com/rescript-lang/syntax/pull/664
- Fix issue where formatter erases tail comments inside JSX tag https://github.com/rescript-lang/syntax/issues/663
- Fix issue where the JSX prop has type annotation of the first class module https://github.com/rescript-lang/syntax/pull/666
- Fix issue where an empty record literal {} expected to have a non-record type would type check https://github.com/rescript-lang/rescript-compiler/pull/5729

#### :eyeglasses: Spec Compliance

- Functions with consecutive dots now print as multiple arrow functions like in JavaScript.

#### :nail_care: Polish

- Add `loading`, `aria-*` DOM element attributes in `JsxDOM.domProps`: `ariaCurrent`, `ariaInvalid`, `ariaAutocomplete`, etc.
- Change the internal representation of props for the lowercase components to record. https://github.com/rescript-lang/syntax/pull/665
- Add `JsxPPXReactSupport` module to relocate the helper functions for JSX v4 from `rescript-react`

# 10.1.0-alpha.2

#### :rocket: New Feature

- Fix pretty printer where it would print doc comments on the same line as other attributes https://github.com/rescript-lang/syntax/pull/642
- Propagte `"jsx"` configuration to dependencies https://github.com/rescript-lang/rescript-compiler/pull/5661
- Add support for empty record literal `{}` for records where all fields are optional https://github.com/rescript-lang/rescript-compiler/pull/5658
- Add support for empty record type (e.g. `type empty = {}`) https://github.com/rescript-lang/rescript-compiler/pull/5658

#### :bug: Bug Fix

- Fix issue in formatting JSX spread props https://github.com/rescript-lang/syntax/pull/644
- Fix location issue in error messages with JSX V4 where the body of the component is an application https://github.com/rescript-lang/syntax/pull/633
- Fix printing of type declarations in error message where they would be considered recursive by default
- Fix issue where the printer would omit attributes for `->` and `|>` https://github.com/rescript-lang/syntax/pull/629
- Fix printing of optional fields in records https://github.com/rescript-lang/rescript-compiler/issues/5654
- Fix printing of comments inside empty blocks https://github.com/rescript-lang/syntax/pull/647

#### :nail_care: Polish

- Improvements and fixes for JSX V4. See guide https://github.com/rescript-lang/syntax/blob/master/cli/JSXV4.md
- Mention all missing fields in error message for records, not just one https://github.com/rescript-lang/rescript-compiler/pull/5657

# 10.1.0-alpha.1

#### :boom: Breaking Change

- Pipe `->` does not support a code block on the right-hand side e.g. `x->{ open A; get("test") }`

#### :rocket: New Feature

- Experimental support for for `async`/`await` https://github.com/rescript-lang/rescript-compiler/pull/5537
- Make `promise` a built-in type https://github.com/rescript-lang/rescript-compiler/pull/5650
- Initial support for JSX V4 including genType, still work in progress.
  - :boom: when V4 is activated, at most one component is allowed for each module.
- Add placeholder types for ES6 collections: `Set`, `Map`, `WeakSet`, and `WeakMap` https://github.com/rescript-lang/rescript-compiler/pull/5630

#### :bug: Bug Fix

- Fix issue with arrays and creation of recursive values https://github.com/rescript-lang/rescript-compiler/pull/5640
- Fix issue where characters such as newlines would be escaped in a template string expression https://github.com/rescript-lang/rescript-compiler/issues/5638
- Fix issue where pipe `->` processing eats up attributes https://github.com/rescript-lang/rescript-compiler/pull/5581
- Fix issue where cancelling `rescript build` would leave the `.bsb.lock` file behind and block future builds

#### :nail_care: Polish

- Print patterns in warnings using rescript printer https://github.com/rescript-lang/rescript-compiler/pull/5492

# 10.0.1

#### :bug: Bug Fix

- Fix issue where watch mode would give an error on Windows https://github.com/rescript-lang/rescript-compiler/pull/5621

# 10.0.0

**Compiler**

#### :boom: Breaking Change

- `bsconfig.json` does not support `// line` comments anymore.
  - Example: `"suffix": ".bs.js" // determine the suffix`
  - Fix: remove the comment and use standard json.
- Changed return type of `Js.String.match_` as it was wrong. [#5070](https://github.com/rescript-lang/rescript-compiler/pull/5070)
  - Example: any use of `Js.String.match_` and `Js.String2.match_`
  - Fix: follow the type errors
- GenType is now vendored in the compiler and drops support for the Flow and untyped back-ends to focus on providing a better experience for TypeScript.
  - Fix: keep on using the older version of the compiler and the separate genType package if Flow support is required. Migrate to TS if one wants to upgrade the compiler version.

#### :rocket: New Feature

- New records with optional fields e.g. `type opt = {x: int, y?: string}` were added as an experimental feature [#5423](https://github.com/rescript-lang/rescript-compiler/pull/5423) [#5452](https://github.com/rescript-lang/rescript-compiler/issues/5452) [New Syntax](https://github.com/rescript-lang/syntax/pull/589/files)
- Add support for `@new @variadic` (see https://github.com/rescript-lang/rescript-compiler/pull/5364)

#### :bug: Bug Fix

- Classify bigint correctly [#5351](https://github.com/rescript-lang/rescript-compiler/pull/5351)
- Fixed crash in `rescript build` on Windows [#5516](https://github.com/rescript-lang/rescript-compiler/pull/5516)
- Fixed `rescript init` command not working [#5526](https://github.com/rescript-lang/rescript-compiler/pull/5526)
- Fix issue with compiler log not terminated that causes problems with editor extension not clearing issues when fixed [#5545](https://github.com/rescript-lang/rescript-compiler/issues/5545)

##### :nail_care: Polish

- Changed Linux build to depend on GLIBC 2.28 again for compatibility with Debian 10.

- Proper M1 support (CI now supports M1 native builds)

**Syntax**

#### :boom: Breaking Change

- `@bs.send.pipe` is now removed. Earlier it was deprecated.
- Missing labels in function application is now an error (https://forum.rescript-lang.org/t/ann-more-strict-checks-in-missed-labels/2117).
  - Example: `let f = (x, ~z) => x + z; f(1, 2)`
  - Fix: do `let f = (x, ~z) => x + z; f(1, ~z=2)` instead
- Externals without `@val` annotations do not work anymore, and externals with `= ""` give an error.
  - Example: `external setTimeout: (unit => unit, int) => float = "setTimeout"` is not supported anymore.
  - Fix: use `@val external setTimeout: (unit => unit, int) => float = "setTimeout"` instead.
  - Example2: `@val external setTimeout: (unit => unit, int) => float = ""` is not supported anymore.
  - Fix2: use `@val external setTimeout: (unit => unit, int) => float = "setTimeout"` instead.
- Strings processed at compile-time don't need escaping anymore.
  - Example: `let blockCommentsRe = %re("/\\/\\*([^*]|[\\r\\n]|(\\*+([^*/]|[\\r\\n])))*\\*+\\//g")`.
  - Fix: use `let blockCommentsRe = %re("/\/\*([^*]|[\r\n]|(\*+([^*/]|[\r\n])))*\*+\//g")` instead.
- Remove parsing of "import" and "export" which was never officially supported https://github.com/rescript-lang/syntax/pull/597 https://github.com/rescript-lang/syntax/pull/599
  - Example: `export type t = int`
  - Fix: `@genType type t = int`
  - Example2: `import realValue: complexNumber => float from "./MyMath"`
  - Fix2: `@genType.import("./MyMath") external realValue: complexNumber => float = "realValue"`

#### :rocket: New Feature

- Unicode is now supported in regular strings and chars (when the symbol fits). This is now going to work: `let str = "Σ"`. And, you'll be able to pattern match on unicode chars: `switch c { | 'Σ' => "what a fine unicode char" | _ => "unicode is fun" }`
- Doc comments `/** ... */` are now supported. Inernally, they are attributes, so are only valid at positions where `@foo` is allowed, or a syntax error is given. Similarly for module-level `/*** comments */` that can go where `@@attributes` go.

#### :bug: Bug Fix

- Fix printing for inline nullary functor types [#477](https://github.com/rescript-lang/syntax/pull/477)
- Fix stripping of quotes for empty poly variants [#474](https://github.com/rescript-lang/syntax/pull/474)
- Implement syntax for arity zero vs arity one in uncurried application in [#139](https://github.com/rescript-lang/syntax/pull/139)
- Fix parsing of first class module exprs as part of binary/ternary expr in [#256](https://github.com/rescript-lang/syntax/pull/256)
- Fix formatter hanging on deeply nested function calls [#261](https://github.com/rescript-lang/syntax/issues/261)

**Libraries**

#### :boom: Breaking Change

- **"Attributes not allowed here"**. If you see this error chances are you're using a ppx that needs updating to a new version.
  See an exampe of how to [update a ppx](https://github.com/zth/rescript-relay/pull/372)
  - Example: for `rescript-relay` 0.23.0 is not supported.
  - Fix: use `rescript-relay@beta` or the new version when released.
- Removed printing modules (Printf, Format etc) and related functions. Details of files added/removed: https://github.com/rescript-lang/rescript-compiler/commit/0fd8bb0e77c4b0e96a9647ac8af614305057003f.

#### :bug: Bug Fix

- Fix library issue with missing `bytes_to_string` https://github.com/rescript-lang/rescript-compiler/issues/5573 https://github.com/rescript-lang/rescript-compiler/pull/5589

#### :nail_care: Polish

- Several Belt / Js libraries are now converted to ReScript syntax, with corresponding comments in Markdown format suitable for hovering. See [#5361](https://github.com/rescript-lang/rescript-compiler/pull/5361).

**Playground**

#### :house: Internal

- Added `jsoo_playground_main.ml` as the rescript-lang.org playground bundle entrypoint

#### :boom: Breaking Change

- Removed Reason syntax support for the playground experience. See https://github.com/rescript-lang/rescript-compiler/pull/5375

---

You can find more old changelog from [docs/changelog](docs/changelog)