Adds a per-fn linearity check that runs on every fn whose
param_modes are all explicit (Borrow or Own, no Implicit), tracks
each binder's consume/borrow state through the AST, and emits
two diagnostics with form-A `suggested_rewrites`:
- `use-after-consume` — a binder is referenced after it has
already been consumed.
- `consume-while-borrowed` — a binder is consumed while a borrow
of it is still live (sibling arg slot, or an enclosing-fn
Borrow param).
Fns with any Implicit param skip the check entirely; that's the
back-compat lane that keeps every existing fixture green. Pure
diagnostic addition: no IR change, no codegen change, no runtime
change.
Each diagnostic carries a non-empty `suggested_rewrites` whose
`replacement` is form-A AILang text (typically `(clone <name>)`).
Adds two new public entrypoints to ailang-surface — `parse_term`
and `term_to_form_a` — so the round-trip
`parse_term(term_to_form_a(t)) ≡ t` is the contract every
emitted replacement must satisfy. Tests assert the contract.
Linearity pass runs only on modules that typechecked clean (any
upstream typecheck error suppresses it for that module — running
on partly-defined IR would produce noise).
Tests: 3 unit tests in `linearity::tests`, 3 integration tests
in `ailang-check/tests/workspace.rs`, 1 serialisation test in
`diagnostic.rs`. `cargo test --workspace` green.
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>
Brummel