Files
AILang/examples/local_rec_let_capture.ail
T
Brummel 26fb3459d8 GREEN: io/print_str byte-faithful via @fputs(@stdout) — closes #29
The runtime print path now writes exactly the bytes of its
argument with no implicit trailing newline. `io/print_str` is
byte-faithful; authors who want a newline emit `(do io/print_str
"\n")` themselves.

## Codegen

`crates/ailang-codegen/src/lib.rs`:
- Module preamble: `@puts(ptr)` → `@fputs(ptr, ptr)` plus
  `@stdout = external global ptr` (libc's `FILE *stdout`).
- Effect-op lowering for `io/print_str`: emit
  `getelementptr +8` then `load ptr, ptr @stdout` then
  `call/tail call i32 @fputs(ptr bytes, ptr fp)`. Identical
  bytes-pointer GEP, distinct sink.
- The pinned IR-shape test renames from
  `print_str_calls_puts_with_bytes_pointer` to
  `print_str_calls_fputs_with_bytes_pointer_and_stdout` and now
  asserts: bytes-GEP present, stdout-load present, both module-
  preamble declarations present, and no `@puts(` call anywhere
  in the emitted IR.

## Why this shape, and not the alternatives

- *Rename `io/print_str` to `io/println_str` (issue #29 option 2)*
  — kept the auto-newline, just relabelled it. AILang's design
  bias is explicit-over-implicit (CLAUDE.md: implicit conversions
  cut). Auto-newline is a hidden runtime augmentation; the rename
  would have preserved it. Rejected.
- *Append `\n` inside the polymorphic `print` (Show-mediated)
  function in `examples/prelude.ail`* — would have been a one-line
  fix. Rejected: `print` is the Show-mediated formatter, not a
  newline emitter; baking a newline into it would have re-imposed
  the same implicit-augmentation problem one layer up, breaking
  callers that legitimately want pure-bytes output.

## Fixture / test sweep

30 `.ail` fixtures whose owning tests asserted line-separated
stdout now emit explicit `(do io/print_str "\n")` after each
print. Tests that asserted on multi-line stdout (`show_print_e2e`,
`floats_e2e`, `str_concat_e2e`, `eq_ord_e2e`, several `print_*`
smoke tests) had their fixtures sweetened the same way; assertions
themselves remain the canonical observable output. Fixtures that
never relied on the newline (no test ever read the absence of one)
were left untouched.

## Migrated metadata

- `crates/ailang-core/tests/hash_pin.rs`: the `ordering_match::main`
  canonical hash is refreshed (`b65a7f834703ffb4` →
  `8ed47b4062ce00f5`). The comment now names both successive
  corpus migrations honestly: the per-type-print-retirement (which
  moved `(do io/print_int x)` to `(app print x)`) AND this
  fputs swap (which wrapped that with `(seq ... (do io/print_str
  "\n"))`).
- `design/contracts/str-abi.md`: the consumer-ABI table now lists
  `@fputs` as the print sink. A prose paragraph documents the
  byte-faithful semantics and references this issue.
- `examples/ordering_match.prose.txt`: regenerated from the
  updated `ordering_match.ail`.
- `crates/ail/tests/snapshots/{hello,sum,max3,list,ws_main}.ll`:
  IR snapshots regenerated via `UPDATE_SNAPSHOTS=1`.
- Stale `@puts` comments in `runtime/str.c`,
  `crates/ail/tests/{e2e,show_print_e2e,print_no_leak_pin}.rs`
  replaced with `@fputs`.

## Verification

- `cargo test -p ail --test print_str_no_auto_newline_e2e` — both
  RED tests from commit c8ecfa3 now pass.
- `cargo test --workspace` — 90 test groups GREEN, 0 failures.
- `cargo build --workspace` — GREEN.
- No new clippy lints (24 warnings pre-existing in
  `crates/ailang-core/src/lib.rs:129`).
- Stats: `bench/orchestrator-stats/2026-05-21-iter-bugfix-print-
  str-fputs.json` — 1/1 tasks, 0 re-loops, 0 review loops.

## Empirical evidence cited

Caught in the 2026-05-21 Qwen3-Coder naming-A/B run
(`experiments/2026-05-21-naming-ab/runs/r1/`): every cohort wrote
`(do io/print_str "...\n")` with explicit `\n` and got doubled
newlines, failing the `t3_main_prints` stdout match across all
three cohorts. The empirical LLM-natural form already assumes the
new (post-this-commit) semantics — confirming the
feature-acceptance test in CLAUDE.md.

closes #29
2026-05-21 12:22:45 +02:00

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; Iter 16b.3 — LetRec captures of `Term::Let`-bound names.
; `count_below(n)` returns how many integers in 1..=n are strictly
; less than a `threshold` computed locally from `n`. The recursive
; helper `loop` captures the let-bound name `threshold` from the
; enclosing scope; its type is only known after typecheck (the
; let-value is `(app + 5 5)` — an `Int` expression, but the desugar
; pass cannot resolve that without inference).
;
; The 16b.2 desugar pass cannot lift this LetRec (capture is Let-bound,
; not fn-param). Instead the desugar pass leaves the LetRec in place;
; the post-typecheck `lift_letrecs` pass in `ailang-check` resolves
; `threshold`'s type as `Int` from the typechecker's env and produces
; a synthetic top-level fn `loop$lr_0(i: Int, n: Int, threshold: Int)
; -> Int`, rewriting every `(app loop ARGS)` to `(app loop$lr_0 ARGS n
; threshold)`.
;
; Expected stdout (one per line):
; count_below(0) = 0 (empty range; loop's first call has i > n)
; count_below(5) = 5 (1..=5; threshold = 10; all 5 are < 10)
; count_below(15) = 9 (1..=15; threshold = 10; 1..=9 are < 10)
(module local_rec_let_capture
(fn count_below
(doc "Count i in 1..=n with i < threshold, where threshold = 5+5.")
(type (fn-type (params (con Int)) (ret (con Int))))
(params n)
(body
(let threshold (app + 5 5)
(let-rec loop
(params i)
(type (fn-type (params (con Int)) (ret (con Int))))
(body
(if (app gt i n)
0
(if (app lt i threshold)
(app + 1 (app loop (app + i 1)))
(app loop (app + i 1)))))
(in (app loop 1))))))
(fn main
(doc "Drive count_below at 0, 5, 15. Expected (per line): 0, 5, 9.")
(type (fn-type (params) (ret (con Unit)) (effects IO)))
(params)
(body
(seq (seq (app print (app count_below 0)) (do io/print_str "\n"))
(seq (seq (app print (app count_below 5)) (do io/print_str "\n"))
(seq (app print (app count_below 15)) (do io/print_str "\n")))))))