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.
39 lines
1.3 KiB
Plaintext
39 lines
1.3 KiB
Plaintext
// Feature 1 — TYPE-position pack projection `xs.T`. The per-element protocol
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// type-arg `T` projects into a Pack of types, usable in type/signature
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// positions: a tuple type `(..xs.T)` and a closure signature
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// `Closure(..xs.T) -> R`. (`T` of each element comes from its
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// `impl Box(T) for <elem>`.)
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#import "modules/std.sx";
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Box :: protocol(T: Type) {
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get :: (self: *Self) -> T;
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}
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IntCell :: struct { v: i64; }
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StrCell :: struct { s: string; }
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Dbl :: struct { n: i64; }
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impl Box(i64) for IntCell { get :: (self: *IntCell) -> i64 => self.v; }
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impl Box(string) for StrCell { get :: (self: *StrCell) -> string => self.s; }
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impl Box(i64) for Dbl { get :: (self: *Dbl) -> i64 => self.n * 2; }
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// Tuple type `(..xs.T)` — heterogeneous (i64, string), matched by the
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// value-projection `(..xs.get)`.
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snap :: (..xs: Box) -> void {
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t : Tuple(..xs.T) = .(..xs.get);
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print("0={} 1={}\n", t.0, t.1);
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}
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// Closure signature `Closure(..xs.T) -> i64` — here `Closure(i64, i64) -> i64`.
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// The closure literal's params are contextually typed from the projection.
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fold :: (..xs: Box) -> i64 {
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cb : Closure(..xs.T) -> i64 = (a, b) => a + b;
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return cb(xs[0].get(), xs[1].get());
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}
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main :: () -> i32 {
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snap(IntCell.{ v = 42 }, StrCell.{ s = "hi" }); // (i64, string)
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print("fold={}\n", fold(IntCell.{ v = 10 }, Dbl.{ n = 5 })); // 10 + 10 = 20
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0
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}
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