Strictly additive new crate per Decision 6 architectural pin.
JSON-AST stays the source of truth; ailang-surface is one
producer/consumer of ailang_core::ast::Module values. ailang-check
and ailang-codegen unchanged.
Crate contents:
- src/lex.rs (~264 LOC): 3-rule lexical core. Whitespace and parens
delimit tokens; semicolon to EOL is comment; first-character
classifier (digit -> int, " -> string, else -> ident).
- src/parse.rs (~1041 LOC): hand-written recursive descent. One Rust
fn per EBNF production. No parser-combinator dep.
- src/print.rs (~371 LOC): deterministic pretty-printer. Round-trip
contract with parse() is the surface's correctness gate.
- tests/round_trip.rs (~128 LOC): integration test runs every
examples/*.ail.json fixture through print -> parse -> canonical
JSON, asserts canonical-byte equality with the original.
Two AST-driven form widenings beyond the 14b sketch (both folded
into DESIGN.md Decision 6):
- lam-term carries (typed name type) params, ret type, and
optional effects (Term::Lam has parallel param_tys/ret_ty/
effects fields).
- import-clause admits (import name (as alias)?) (Import.alias
is Option<String>).
Production count ~28, under 30-rule budget. Constraint 1
(formalisable for foreign LLM) intact.
Verification:
- cargo build --workspace green.
- cargo test --workspace: 76 tests green (was 64; +9 surface unit,
+2 round-trip integration). All 17 fixtures round-trip
byte-identical at canonical level. 3 hand-written .ailx
exhibits parse to canonical JSON identical to their .ail.json
siblings.
- cargo doc --no-deps zero warnings (DESIGN.md item 6 invariant).
Manual smoke test (ail parse → ail run): hello, box,
list_map_poly all produce expected output through the form-(A)
authoring lane end-to-end.
CLI: ail parse <file.ailx> [-o <file.ail.json>]. .ail.json
remains a first-class input to every existing subcommand.
Plan 14d: stdlib (std_list.ailx with length/filter/fold/concat/
reverse/head/tail), authored in form (A) from day one.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
User redirected at iter boundary: writing a stdlib in JSON was
the wrong move. The language is supposed to be the one I program
*best* in, and JSON-AST authoring is rationalisation, not
strength.
DESIGN.md Decision 6 captures the constraints that fall out of
the "formalisable for a foreign LLM" hard requirement (no
precedence, no semantic indentation, ASCII only, every AST node
a uniquely-tagged form), sketches three candidate notations with
the same `map` encoded in each, and picks form (A) — fully-tagged
S-expressions — as the first attempt with explicit rollback path
to form (C) if (A) hurts authoring.
Form (A) shape:
- 3-rule lexical core: sexpr / atom / token-classified-by-
first-character.
- Every AST node has a unique head keyword. No case-rule (no
"capitalised head means ctor"); ctors are explicit via
`(term-ctor TypeName CtorName args)` and `(pat-ctor CtorName
fields)`.
- Bare atoms get their sort from the parent slot (type-var
inside `(con NAME args)`, term-var inside `(app HEAD args)`,
pat-var inside `(pat-ctor CTOR fields)`, integer literal in
term position, etc.).
Empirical exhibits, hand-encoded:
- examples/hello.ailx 5 LOC (JSON was 36 pretty / 21 canonical)
- examples/box.ailx 25 LOC (JSON was 160 / 88)
- examples/list_map_poly.ailx 50 LOC (JSON was 394 / 230)
4-8x line reduction, ~4x character reduction. Bigger gains on
bigger programs since overhead is proportional to AST depth.
None are parseable yet — header comments say "Iter 14b design
exhibit, parser lands in 14c".
Two small spec issues caught while writing the exhibits and
folded back into DESIGN.md before committing:
- Operator idents (`+`, `==`) need the token-by-first-char
classification rule, not a word-shaped regex.
- Bool literals (`true`/`false`) reserved in term context;
unit is explicit `(lit-unit)`.
Tests unchanged (this iter is paper). 25/25 e2e green.
cargo doc --no-deps zero warnings.
Plan 14c: new crate `ailang-surface` with PEG parser, round-trip
hash-equivalence gate against every existing `examples/*.ail.json`,
CLI subcommand `ail parse`. If round-trip holds, stdlib starts
in `.ailx` form (Iter 14d).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Brummel