Brummel
d5f63bc3e5
Lift 16b.1's no-capture restriction. The desugar pass's `scope` becomes a `BTreeMap<String, ScopeEntry>` carrying `KnownType` for fn/Lam-params, sentinels for Let-/Match-bindings. LetRec captures of `KnownType` names are lifted: the synthetic top-level fn's signature gets the capture types appended, and every call site of the LetRec name is rewritten via `subst_call_with_extras` to pass the captures positionally. Captures from let-bindings, match-arm patterns, polymorphic enclosing fns, and name-as-value uses are rejected at desugar with panics pointing at 16b.3-16b.7. Demo: `sum_below(n)` recurses via `(let-rec loop (params i) ... (body ... uses n ...) (in (app loop 1)))`. Lifts to `loop$lr_0(i: Int, n: Int) -> Int` with `(app loop X)` rewritten to `(app loop$lr_0 X n)`. Outputs 0, 10, 45. Tests: 103 -> 106 (+1 e2e local_rec_capture_demo, +2 desugar unit; the 16b.1 capture-panic test was repurposed into the positive fn-param-capture test). Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>