1c14383495
Generic value-carrying failable composition works with the documented
$T: Type generic form (catch / destructure / failure-propagation / a
second monomorphization at a different T). Issue 0062 was an invalid-repro
report — it used the non-generic T: type form, which is a plain Type-valued
param, not a generic type parameter. Marked 0062 resolved (not a bug).
The only real residual: a non-$ T: Type function param used as a type
silently resolves to an empty {} (renders T{}) instead of erroring. Filed
as 0064 (deferred, orthogonal to ERR — the $T idiom works).
Regression: 1044-errors-generic-failable-composition.sx.
30 lines
1.3 KiB
Plaintext
30 lines
1.3 KiB
Plaintext
// Generic function with a value-carrying `!` return composes (ERR E5.1
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// sub-feature 8). A `$T: Type` generic whose return is `(T, !E)` monomorphizes
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// per call: `return try f()` propagates the closure's error, and each
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// monomorphization's success value flows through as the concrete `T`.
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// (Regression: confirms issue 0062 was an invalid-syntax repro — the bug only
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// appeared with the non-generic `T: Type` form; the `$T` form works.)
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#import "modules/std.sx";
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E :: error { Bad }
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wrap :: ($T: Type, f: Closure() -> (T, !E)) -> (T, !E) { return try f(); }
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main :: () -> s32 {
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// success, consumed by catch
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print("catch={}\n", wrap(s32, closure(() -> (s32, !E) { return 7; })) catch e -1); // 7
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// success, consumed by destructure (binds value + error slot)
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r, err := wrap(s32, closure(() -> (s32, !E) { return 9; }));
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no_err := if err == error.Bad then false else true;
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print("destr={} ok={}\n", r, no_err); // destr=9 ok=true
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// failure path: the raised tag propagates through the generic `try`
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print("fail={}\n", wrap(s32, closure(() -> (s32, !E) { raise error.Bad; }) ) catch e -1); // -1
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// a second monomorphization at a different T
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print("u8={}\n", wrap(u8, closure(() -> (u8, !E) { return 200; })) catch e 0); // 200
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return 0;
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}
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