concat-notation

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A Racket implementation of RFC 9402 Concat Notation.

Concat Notation is a text-based language for describing pictures and videos featuring cats, containers, and their interactions. This project implements complete syntax parsing and ASCII art rendering.

Installation

$ raco pkg install https://github.com/13m0n4de/concat-notation.git

Usage

REPL:

$ concat-notation
Concat Notation (RFC 9402) REPL
Enter expressions (Ctrl+D to exit)

concat> cat
  |\      _,,,---,,__
  /,`.-'`'    -.  ;--;;,_
 |,4-  ) )-,_..;\ (   `'-'
'---''(_/--'  `-'\_)

Command-line evaluation:

$ concat-notation -e "[cat]"
[  |\      _,,,---,,__     ]
[  /,`.-'`'    -.  ;--;;,_ ]
[ |,4-  ) )-,_..;\ (   `'-']
['---''(_/--'  `-'\_)      ]

Run a file:

$ concat-notation examples/adjacent.concat
  |\      _,,,---,,__        |\      _,,,---,,__        __
  /,`.-'`'    -.  ;--;;,_    /,`.-'`'    -.  ;--;;,_  .'..`.
 |,4-  ) )-,_..;\ (   `'-'  |,4-  ) )-,_..;\ (   `'-' |"'.';
'---''(_/--'  `-'\_)       '---''(_/--'  `-'\_)        `--`~

Debug mode:

$ concat-notation -d -e "cat + @"
AST:
'(sequence
  (position
   (adjacent
    (adjacent (over (multiple (concat (subject "cat")))))
    "+"
    (over (multiple (concat (subject (yarn-ball "@"))))))))

OUTPUT:
  |\      _,,,---,,__        __
  /,`.-'`'    -.  ;--;;,_  .'..`.
 |,4-  ) )-,_..;\ (   `'-' |"'.';
'---''(_/--'  `-'\_)        `--`~

Syntax Reference

Syntax	Description	Example
cat	Complete cat	cat
c, a, t	Cat parts (head, body, tail)	c[a]t, c + a + t
catN	Cat with subscript (N is a number)	cat1 + cat2 => cat2 + cat1
@	Yarn ball	cat + @
[], (), {}, <>	Containers	[cat], <cat>
+	Adjacent (horizontal composition)	cat + cat
/	Over (vertical stacking)	cat / cat
=>	Sequence (temporal progression, change)	cat => @
N*expr, Nexpr	Horizontal repetition N times	3*cat, 3cat
N/expr	Vertical repetition N times	2/cat

Grammar Specification

This project uses a BNF grammar (grammar.rkt) that is functionally equivalent to the ABNF grammar in RFC 9402.

sequence : position
         | position "=>" sequence

position : adjacent

adjacent : over
         | adjacent "+" over

over : multiple
     | multiple "/" position

multiple : concat
         | NUMBER ["*"] multiple
         | NUMBER "/" multiple

concat : subject [NUMBER]
       | [partial-cat] container [partial-cat]

container : LSQUARE opt-pos RSQUARE
          | LPAREN opt-pos RPAREN
          | LCURLY opt-pos RCURLY
          | LANGLE opt-pos RANGLE
opt-pos : [position]

subject : CAT
        | partial-cat
        | yarn-ball
        | text

partial-cat: PARTIAL
yarn-ball : "@"
text: ALPHA+

Examples

$ concat-notation -e "c[a]t"
  |\  [    _,,,---,,_]_
  /,`.[-'`'    -.  ;-]-;;,_
 |,4- [ ) )-,_..;\ ( ]  `'-'
'---''[(_/--'  `-'\_)]

$ concat-notation -e "c[ c[cat]t / c[@]t ]"
  |\  [  |\  [  |\      _,,,---,,__     ]_     ]
  /,`.[  /,`.[  /,`.-'`'    -.  ;--;;,_ ]-;;,_ ]
 |,4- [ |,4- [ |,4-  ) )-,_..;\ (   `'-']  `'-']
'---''['---''['---''(_/--'  `-'\_)      ]      ]
      [                                        ]
      [  |\  [  __  ]_                         ]
      [  /,`.[.'..`.]-;;,_                     ]
      [ |,4- [|"'.';]  `'-'                    ]
      ['---''[ `--`~]                          ]

$ concat-notation -e "@/cat1 + @/cat2 => cat2/@ + cat1/@"
  __                         __                            |\      _,,,---,,__    2   |\      _,,,---,,__    1
.'..`.                     .'..`.                          /,`.-'`'    -.  ;--;;,_    /,`.-'`'    -.  ;--;;,_
|"'.';                     |"'.';                         |,4-  ) )-,_..;\ (   `'-'  |,4-  ) )-,_..;\ (   `'-'
 `--`~                      `--`~                        '---''(_/--'  `-'\_)       '---''(_/--'  `-'\_)
                                                      =>
  |\      _,,,---,,__    1   |\      _,,,---,,__    2      __                         __
  /,`.-'`'    -.  ;--;;,_    /,`.-'`'    -.  ;--;;,_     .'..`.                     .'..`.
 |,4-  ) )-,_..;\ (   `'-'  |,4-  ) )-,_..;\ (   `'-'    |"'.';                     |"'.';
'---''(_/--'  `-'\_)       '---''(_/--'  `-'\_)           `--`~                      `--`~

For more examples, see examples.