Fix all mypy errors and make mypy a CI gate

- bindb.py: stop reusing 'm' for both List[BIN_Tuple] and the
  Optional[BIN_Tuple] result of StaticPhrases.lookup()
- reynir.py: annotate _Sentence._tree (and the local in parse()) as
  Optional[Node] instead of letting mypy infer type None
- Add types-cffi to the dev dependency group so eparser_build.py
  type-checks
- Run mypy in CI on all non-PyPy jobs now that it is clean

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: vthorsteinsson

.github/workflows/python-package.yml

@@ -32,6 +32,10 @@ jobs:
       run: uv sync --locked
     - name: Lint with ruff
       run: uv run ruff check src/reynir
+    - name: Type check with mypy
+      # mypy is not installed on PyPy (see [dependency-groups] in pyproject.toml)
+      if: ${{ !startsWith(matrix.python-version, 'pypy') }}
+      run: uv run mypy src/reynir
     - name: Test with pytest
       run: uv run pytest
     - name: Slack notification

pyproject.toml

@@ -58,6 +58,7 @@ dev = [
     "pytest",
     "ruff",
     "mypy; implementation_name != 'pypy'",
+    "types-cffi",
     "setuptools",
 ]
 

src/reynir/bindb.py

@@ -131,8 +131,8 @@ def lookup_name_gender(self, name: str, preferred_case: str = "nf") -> str:
 
         # The first name was not found: check whether the full name is
         # in the static phrases
-        m = StaticPhrases.lookup(name)
-        if m is not None:
-            if m.fl in PERSON_NAME_FL:
-                return m.ordfl
+        sp = StaticPhrases.lookup(name)
+        if sp is not None:
+            if sp.fl in PERSON_NAME_FL:
+                return sp.ordfl
         return "hk"  # Unknown gender

src/reynir/reynir.py

@@ -131,7 +131,7 @@ def __init__(self, job: "_Job", s: TokenList) -> None:
         self._err_index: Optional[int] = None
         self._error: Optional[ParseError] = None
         self._simplified_tree: Optional[SimpleTree] = None
-        self._tree = None
+        self._tree: Optional[Node] = None
         # Number of possible combinations
         self._num: Optional[int] = None
         # Score of best parse tree
@@ -154,7 +154,7 @@ def parse(self) -> bool:
         job = self._job
         num = 0
         score = 0
-        tree = None
+        tree: Optional[Node] = None
         try:
             # Invoke the parser on the sentence tokens
             tree, num, score = job.parse(self._s)