e4d24476a9
REIFY Phase 1.0. Add examples/0615: a type-fn `Box :: ($T)->Type {
return reify(...) }` used at two independent sites (a return type and a
parameter type); consume(build()) typechecks only if both sites resolve
to ONE TypeId. RED by design — reify in a type-fn body still bails
("only supported in a :: binding"). Phase 1.1 routes a reify-returning
type-fn body through reifyType under the mangled instantiation name so
identity holds, turning this green.
35 lines
1.2 KiB
Plaintext
35 lines
1.2 KiB
Plaintext
// REIFY Phase 1: a type-fn that RETURNS `reify(...)` must memoize by the
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// instantiation's mangled name, so `Box(i64)` resolved at two INDEPENDENT sites
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// (here: a return type and a parameter type) is ONE `TypeId`. A value built at
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// one site is therefore assignable / matchable at the other — nominal identity
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// (Contract 1). If the reify result were not registered under the mangled
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// instantiation name, the two sites would mint distinct types and
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// `consume(build())` would be a type error.
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#import "modules/std.sx";
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#import "modules/std/meta.sx";
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Box :: ($T: Type) -> Type {
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return reify(.enum(.{ variants = .[
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EnumVariant.{ name = "some", payload = T },
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EnumVariant.{ name = "none", payload = void },
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] }));
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}
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build :: () -> Box(i64) { // site A resolves Box(i64)
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return Box(i64).some(7);
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}
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consume :: (b: Box(i64)) { // site B resolves Box(i64) independently
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if b == {
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case .some: (n) { print("some {}\n", n); }
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case .none: { print("none\n"); }
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}
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}
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main :: () -> i32 {
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consume(build()); // typechecks ONLY if site A == site B
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b : Box(i64) = .none;
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consume(b);
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return 0;
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}
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