213cedf0b5
The trailing-`!`-after-the-value-type spelling (`-> T !`, `-> Tuple(A,B) !`) was a
redundant second way to write a failable return that the parser folded into the
same AST as the parenthesized `(T, !)` / `(A, B, !)` result list. Remove it so
there is ONE canonical spelling: the error channel always rides as the last slot
of the parenthesized list.
- parser: `parseFnReturnType` no longer folds a trailing `!` after a value type —
it rejects it with a located diagnostic ("a failable return is written `(T, !)`
… not `T !`"). This one chokepoint covers fn declarations, lambdas, fn-pointer
types `(A) -> R`, and closure types `Closure(A) -> R`. The error-ONLY `-> !` /
`-> !ErrSet` form is unaffected (parsed by parseTypeExpr as an error_type_expr).
- migrated every usage to canonical form across library/ + examples/ + issues/ +
tests/: `-> T !E` → `-> (T, !E)`; the value-carrying `-> Tuple(A, B) !` (which
FLATTENED to a multi-value failable) → `-> (A, B, !)`, preserving behavior. A
genuine single-tuple-value failable stays `-> (Tuple(A,B), !)`.
- parser unit tests: the "bare form folds" tests become "bare form is rejected";
canonical-form parse tests retained.
- docs: specs.md §12 + scattered refs and readme.md updated to the `(T, !)` form.
Behavior-preserving (the bare form was sugar for the same AST). Adversarial review
confirmed: rejection complete across all positions, every canonical form works on
both success/error paths, error-only `-> !` intact, no crashes. Full suite green
(unit tests + 850 corpus examples).
32 lines
984 B
Plaintext
32 lines
984 B
Plaintext
// Comptime `#run` of a failable composes with the handlers exactly as at
|
|
// runtime: `catch` absorbs, `or` terminates, a successful bare `#run` yields the
|
|
// value (error channel stripped), and an `onfail` in the evaluated body still
|
|
// runs during comptime unwinding (E5.2).
|
|
|
|
#import "modules/std.sx";
|
|
|
|
E :: error { Bad, Empty }
|
|
|
|
parse :: (n: i32) -> (i32, !E) {
|
|
if n < 0 { raise error.Bad; }
|
|
if n == 0 { raise error.Empty; }
|
|
return n * 2;
|
|
}
|
|
|
|
guard :: (ok: bool) -> !E {
|
|
onfail print("comptime cleanup\n");
|
|
if !ok { raise error.Bad; }
|
|
return;
|
|
}
|
|
|
|
ok_v :: #run parse(5); // success → 10 (value, error stripped)
|
|
caught :: #run parse(-1) catch (e) 99; // Bad → 99
|
|
ored :: #run parse(0) or 55; // Empty → 55
|
|
|
|
#run guard(false) catch (e) { }; // onfail fires during the comptime unwind
|
|
|
|
main :: () -> i32 {
|
|
print("ok={} caught={} ored={}\n", ok_v, caught, ored);
|
|
return ok_v + caught + ored; // 10 + 99 + 55 = 164
|
|
}
|