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).
40 lines
1.7 KiB
Plaintext
40 lines
1.7 KiB
Plaintext
// Failable `or` chains (ERR step E2.4b). `lhs or rhs` with failable operands
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// is a left-to-right, short-circuit chain: each failing attempt routes to the
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// next operand; the chain resolves when an operand succeeds (or a value
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// terminator absorbs). `try` marks an operand whose failure is visible routing
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// (path-marker rule); a bare failable operand is allowed when a downstream
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// terminator absorbs it. A `catch` over a parenthesized chain redirects the
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// chain's total failure to the handler instead of the function. Absorbed
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// failures clear the trace buffer; `onfail` does not fire for a failure that
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// never leaves its block. This run takes only absorbed paths → exit 120.
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#import "modules/std.sx";
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E :: error { A, B };
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fa :: (n: i32) -> (i32, !E) {
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if n == 0 { raise error.A; }
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if n < 0 { raise error.B; }
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return n;
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}
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fv :: (n: i32) -> !E { // void (pure) failable
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if n == 0 { raise error.A; }
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return;
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}
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main :: () -> (i32, !E) {
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onfail print("onfail fired (BUG)\n"); // must NOT fire — every chain below absorbs
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r : i32 = 0;
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r = r + (try fa(0) or try fa(7)); // a fails → b succeeds → 7
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r = r + (try fa(0) or try fa(0) or try fa(3)); // first two fail → third → +3 = 10
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r = r + (fa(0) or fa(0) or 96); // bare chain + value terminator → +96 = 106
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r = r + ((try fa(0) or try fa(0)) catch (e) 5); // both fail → catch handler → +5 = 111
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r = r + ((try fa(0) or try fa(9)) catch (e) 0); // second succeeds → catch skipped → +9 = 120
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try fv(0) or try fv(1); // void chain: first fails → second succeeds
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return r; // success → exit 120; onfail skipped
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}
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