Step 12: Parser combinator library — pure SX, 68 tests
lib/parser-combinators.sx — 46 definitions in 8 layers:
0. Result constructors (make-ok, make-fail, ok?, result-value, etc.)
1. Primitives (satisfy, parse-char, any-char, parse-string, eof)
2. Core combinators (fmap, parse-bind, seq, alt, label, lazy-parser)
3. Repetition (many, many1, optional, skip-many)
4. Structural (between, sep-by, sep-by1, skip-left, skip-right,
not-followed-by, look-ahead)
5. Character classes (digit, letter, alpha-num, whitespace, skip-spaces)
6. Literal parsers (number-literal, string-literal, identifier)
7. Run function (run-parser)
8. SX tokenizer (sx-comment, sx-keyword, sx-symbol, sx-number,
sx-string, sx-token, sx-tokenize)
Self-tests by tokenizing SX: (define x 42), {:ok true}, (+ 1 (* 2 3)),
comments, negative numbers, nested parens, recursive grammars.
No evaluator changes. Pure HO functions + thunks for lazy recursion.
2868/2868 tests, zero failures.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
giles
516f9c7186