bdd0e96d78
A block's value is now its last statement ONLY when that statement is a trailing expression with no `;`. A trailing `;` discards the value, leaving the block void. This makes value-vs-statement explicit and lets the compiler reject "this block was supposed to produce a value". Compiler: - Parser records `Block.produces_value` (last stmt is a no-`;` trailing expression) + `Block.discarded_semi` (the `;` that discarded a value), via `expectSemicolonAfter`. A trailing expression before `}` may now omit its `;` (previously a parse error). Match-arm and else-arm bodies are built value-producing regardless of the arm `;` (arms are exempt — the `;` is an arm terminator). - Lowering: `lowerBlockValue` / the block-expr path / `inferExprType` respect `produces_value`. A value-position block that discards its value is a hard error (`lowerValueBody` for function bodies; the value-context `.block` path for if/else branches, `catch` bodies, value bindings, match arms). Pure-failable `-> !` bodies (value rides the error channel) and a value-if whose branches are void are handled without false errors. - `defer`/`onfail` cleanup bodies lower as statements (void), so a trailing `;` there is fine. Migration (behavior-preserving — output unchanged): - stdlib + ~210 examples: dropped the trailing `;` on value-position last expressions. `format` now ends with an explicit `#insert "return result;"` (it relied on `#insert`-as-block-value, which `;` discards). - Two `main :: () -> s32` examples that relied on the old silent default-return got an explicit trailing `0`. - Rejection snapshots 0412 / 1013 regenerated (their quoted source lines lost a `;`); the diagnostics themselves are unchanged. Docs/tests: specs.md "Block values" section; examples 0040 (rules) + 0041 (rejection); 3 parser unit tests. Filed issue 0066 (pre-existing match-arm negated-literal phi-width quirk, surfaced not caused here). Gates: zig build, zig build test, run_examples.sh -> 343 passed, cross_compile.sh -> 7 passed (also refreshed its stale example names).
29 lines
1.1 KiB
Plaintext
29 lines
1.1 KiB
Plaintext
// Step 2.5 — contextual typing for closure literals with N (heterogeneous)
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// params. An untyped lambda `(a, b, c) => ...` takes each param's type
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// positionally from the expected `Closure(T0, T1, T2) -> R` signature, in both
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// assignment and argument position. (Previously only the first param — or
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// all-same-typed params — resolved; trailing params silently defaulted to s64.)
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#import "modules/std.sx";
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// argument-position: lambda typed from the parameter's closure type.
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apply2 :: (f: Closure(s64, string) -> s64, x: s64, s: string) -> s64 {
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return f(x, s);
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}
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apply3 :: (f: Closure(s64, s64, string) -> s64, a: s64, b: s64, c: string) -> s64 {
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return f(a, b, c);
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}
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main :: () -> s32 {
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// assignment-position, mixed (s64, string) params — `b` is string.
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cb : Closure(s64, string) -> s64 = (a, b) => a + b.len;
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print("cb={}\n", cb(10, "hello")); // 10 + 5 = 15
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// argument-position, 2 params.
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print("r={}\n", apply2((a, b) => a + b.len, 10, "hello")); // 15
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// argument-position, 3 params (s64, s64, string).
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print("q={}\n", apply3((a, b, c) => a + b + c.len, 1, 2, "xyz")); // 1+2+3 = 6
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0
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}
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