lab/sx
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

refactor: canonical failable syntax (T, !) — remove the bare -> T ! sugar

Browse Source 
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).
This commit is contained in:
agra
2026-06-27 18:11:20 +03:00
parent b322dcfe61
commit 213cedf0b5
53 changed files with 184 additions and 232 deletions
Download Patch File Download Diff File Expand all files Collapse all files

14
examples/errors/1040-errors-failable-closure-composition.sx
View File

@@ -12,21 +12,21 @@
E :: error { Neg }
bare :: (cb: (i64) -> i64 !E, n: i64) -> i64 { return cb(n) catch (e) -1; }
chain :: (cb: Closure(i64) -> i64 !E, n: i64) -> i64 !E { return try cb(n); }
bare :: (cb: (i64) -> (i64, !E), n: i64) -> i64 { return cb(n) catch (e) -1; }
chain :: (cb: Closure(i64) -> (i64, !E), n: i64) -> (i64, !E) { return try cb(n); }
dbl :: (x: i64) -> i64 !E { if x < 0 { raise error.Neg; } return x * 2; }
dbl :: (x: i64) -> (i64, !E) { if x < 0 { raise error.Neg; } return x * 2; }
main :: () -> i32 {
// failable closure literal through a bare fn-type param (matching ABI)
print("bare ok={} err={}\n",
bare(closure((x: i64) -> i64 !E { if x < 0 { raise error.Neg; } return x * 2; }), 5),
bare(closure((x: i64) -> i64 !E => x * 2), -1)); // ok=10; err: arrow never raises → cb(-1) = -2
bare(closure((x: i64) -> (i64, !E) { if x < 0 { raise error.Neg; } return x * 2; }), 5),
bare(closure((x: i64) -> (i64, !E) => x * 2), -1)); // ok=10; err: arrow never raises → cb(-1) = -2
// Closure(...) param, try-propagated, then caught at the call site
print("chain ok={} err={}\n",
chain(closure((x: i64) -> i64 !E => x + 6), 4) catch (e) 0, // 10
chain(closure((x: i64) -> i64 !E { raise error.Neg; }), 1) catch (e) 0); // 0
chain(closure((x: i64) -> (i64, !E) => x + 6), 4) catch (e) 0, // 10
chain(closure((x: i64) -> (i64, !E) { raise error.Neg; }), 1) catch (e) 0); // 0
// NON-failable closure literal widened into the failable bare slot
print("widen={}\n", bare(closure((x: i64) -> i64 => x + 1), 9)); // 10