989e18b760
Replace the bare-paren tuple grammar with explicit, position-unambiguous
forms, mirroring how structs work:
type `(A, B)` -> `Tuple(A, B)` (named keeps `:`)
value `(a, b)` -> `.(a, b)` (named uses `=`)
typed (new) -> `Tuple(A, B).(a, b)` (like `Point.{...}`)
failable `-> (T, !)` -> `-> T !`
`-> (T1, T2, !)`-> `-> Tuple(T1, T2) !` (channel outside Tuple)
Bare `(...)` is now grouping only, everywhere; a comma in bare parens is a
hard error with a migration hint. Grouping, function types `(A, B) -> R`,
param lists, lambdas, and match bindings are unaffected.
`Tuple(...)` is strictly a TYPE in every position (including `size_of` /
`type_info` args); a tuple VALUE comes only from `.(...)` (anonymous) or
`Tuple(...).(...)` (explicitly typed). A bare `Tuple(1, 2)` is a tuple
type with non-type elements -> rejected.
The ~110 tuple-bearing corpus files were migrated with a one-shot
AST-aware migrator (the `sx migrate` tool from the prior commit, removed
here). New examples: 0130 (new syntax), 0131 (typed construction), 1060
(named-tuple failable return). 1116 golden updated for the new hint text.
61 lines
2.1 KiB
Plaintext
61 lines
2.1 KiB
Plaintext
// Consuming value-carrying failables with `try` and `catch` (ERR step E2.1b —
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// the consumer side of the error-channel tuple ABI). `try f()` on a
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// `-> (T, !E)` callee binds the value slot on success and propagates the error
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// on failure (a pure-failable caller returns the tag; a value-carrying caller
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// returns `{undef, tag}`). `f() catch (e) BODY` yields the value slot on success
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// or the handler body's value on failure, merged through a block parameter.
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// The producer side is `examples/228-value-failable.sx`.
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#import "modules/std.sx";
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E :: error { Bad, Empty }
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parse :: (n: i32) -> i32 !E {
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if n < 0 { raise error.Bad; }
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if n == 0 { raise error.Empty; }
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return n * 2;
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}
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// value-carrying `try` in a value-carrying caller — propagates {undef, tag}.
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inc :: (n: i32) -> i32 !E {
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v := try parse(n);
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return v + 1;
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}
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// value-carrying `try` in a pure-failable caller — propagates the tag.
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relay :: (n: i32) -> !E {
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v := try parse(n);
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if v < 0 { raise error.Bad; }
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return;
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}
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// value-carrying `catch`, bare-expression fallback.
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safe :: (n: i32) -> i32 {
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return parse(n) catch (e) 0;
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}
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// value-carrying `catch`, match-body value.
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classify :: (n: i32) -> i32 {
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return parse(n) catch (e) == {
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case .Bad: 1;
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case .Empty: 2;
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else: 3
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};
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}
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main :: () -> i32 {
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r : i32 = 0;
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a, ea := inc(5); // parse(5)=10 → v=10 → 11
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if !ea { r = r + a; } // success → +11 (value live only when proven ok)
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b, eb := inc(-1); // parse(-1)=Bad → propagate {undef, Bad}
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if eb == error.Bad { r = r + 4; } // true → +4
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er := relay(3); // parse(3)=6 ok → relay ok
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if er == error.Bad { r = r + 50; } // false
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r = r + safe(7); // parse(7)=14 → +14
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r = r + safe(-1); // Bad → catch → 0
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r = r + classify(-1); // Bad → 1
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r = r + classify(0); // Empty → 2
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print("consume result: {}\n", r); // 11+4+14+0+1+2 = 32
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return r;
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}
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