76689a1ea6
A function may return multiple values via a bare-paren return signature: `-> (A, B)` / `-> (x: A, y: B)` / `-> (A, B, !)` (error always the last slot), and `-> ()` is `void`. This is DISTINCT from a `Tuple(…)` value — return-position only (a dedicated `ReturnTypeExpr` AST node resolving to a reused `.tuple` TypeId); a parameter / field / variable annotation `x: (A, B)` is rejected. A single-value `-> (T, !)` stays a plain failable (= `-> T !`). Returns use the bare comma form `return a, b` / `return x = a, y = b` (no `.( … )` literal). Consume by destructuring (`a, b := f()`) or single-bind + field access (`c := f(); c.sum`); a failable bound value holds only the value slots (the error stays on the `!` channel). Named return slots are in-scope assignable locals; with no explicit `return` the implicit return is synthesized from them. Path-sensitive definite-assignment enforces the must-set rule, and a slot may carry a default that exempts it. Validation rejects arity mismatches, out-of-slot-order named elements, a slot/parameter name collision, a comma list from a single-value function, and a multi-return signature used as a value type. Examples 0202-0213; readme + specs updated. issues/0197 files a pre-existing annotated-assignment type-check gap (`x: i32 = "hi"` segfaults) surfaced by the adversarial review.
22 lines
696 B
Plaintext
22 lines
696 B
Plaintext
// Empty parens `()` as a return type mean `void`: `f :: () -> () { … }` is
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// exactly `f :: () -> void { … }`. The zero-parameter FUNCTION type `() -> R`
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// (a callable taking no args) is unaffected — only an empty `()` in the
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// return-TYPE slot folds to void.
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#import "modules/std.sx";
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// `-> ()` is void: no value returned.
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greet :: () -> () { print("hi\n"); }
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// A `-> void` spelling, for contrast — identical behavior.
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greet2 :: () -> void { print("bye\n"); }
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// Zero-param function-typed parameter still parses as a callable, not void.
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run :: (f: () -> i64) -> i64 { return f(); }
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main :: () -> i64 {
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greet();
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greet2();
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print("{}\n", run(() => 7));
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return 0;
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}
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