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).
26 lines
1.1 KiB
Plaintext
26 lines
1.1 KiB
Plaintext
// Program-wide closure-shape union — widening REJECTION (ERR E5.1 sub-feature 2).
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// Two closure literals of shape `Closure(i32)->(i32,!)` raise `Negative` /
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// `Other`; the shared inferred-`!` node for that shape is { Negative, Other }.
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// A caller that `try`s a slot of this shape but declares only `!Small` (which
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// omits both tags) is rejected — the union is checked against the caller's set
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// even though the call goes through a slot with no static function name.
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#import "modules/std.sx";
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Small :: error { Unrelated }
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reject :: (h: Closure(i32) -> (i32, !), x: i32) -> (i32, !Small) {
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return try h(x); // Negative, Other ∉ Small → two diagnostics
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}
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main :: () -> i32 {
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gpa := GPA.init();
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push Context.{ allocator = xx gpa } {
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handlers : List(Closure(i32) -> (i32, !)) = .{};
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handlers.append(closure((x: i32) -> (i32, !) { if x < 0 { raise error.Negative; } return x; }));
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handlers.append(closure((x: i32) -> (i32, !) { if x == 0 { raise error.Other; } return x; }));
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print("r={}\n", reject(handlers.items[0], 5) catch (e) 0);
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}
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return 0;
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}
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