9306ad570d
REIFY Phase 3.1. Add RecvResult($T) and TryResult($T) to meta.sx as type-fns over reify (value-or-closed; value-or-empty-or-closed). They need NO new compiler machinery — reify-of-a-literal in a type-fn body is exactly the Phase 1 path — so the channel result types are pure sx library code. examples/0617 green (both construct + match, incl. payload-less .closed / .empty). Suite green (673 examples, 447 unit). make_enum(variants) (3.2) and type_info (2.2) remain — both blocked on a generalized reify reader (reifyType currently AST-walks a literal TypeInfo). Plan/checkpoint updated.
65 lines
2.7 KiB
Plaintext
65 lines
2.7 KiB
Plaintext
// Comptime type metaprogramming (REIFY) — `type_info` / `reify` / `field_type`
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// plus the data model they reflect INTO and construct FROM. Mirrors the Zig
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// `@typeInfo` / `@Type` split: reflect a type → data, construct a NEW nominal
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// type from data.
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//
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// This is a SEPARATE on-demand module rather than part of the prelude: its data
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// types would otherwise intern into every module's type table and shift every
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// `.ir` snapshot. Import it explicitly: #import "modules/std/meta.sx";
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//
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// `reify` / `type_info` / `field_type` are comptime-only builtins — a `reify`
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// reached at runtime is a hard error (the type must be minted at compile time).
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// One variant of a reify'd enum: a name plus an optional payload type.
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// `payload = void` means a tagless variant (e.g. `closed`).
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EnumVariant :: struct {
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name: string;
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payload: Type;
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}
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// The shape of an enum/tagged-union being reflected or constructed.
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EnumInfo :: struct {
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variants: []EnumVariant;
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}
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// The reflected/constructed type shape. A tagged union over the kinds of type
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// `reify` can mint. Phase 0 ships only `` .`enum ``; struct/tuple land later.
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// The variant uses the backtick raw-identifier escape so it reads as the
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// keyword `enum` (`` reify(.`enum(...)) ``) rather than a mangled `enum_`.
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TypeInfo :: enum {
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`enum: EnumInfo;
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}
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// reify(info) — mint a NEW nominal type from a `TypeInfo` (comptime-only).
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// type_info($T) — reflect an existing type into a `TypeInfo`.
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// field_type($T, i) — the i-th field/variant payload type of `$T`.
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reify :: (info: TypeInfo) -> Type #builtin;
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type_info :: ($T: Type) -> TypeInfo #builtin;
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field_type :: ($T: Type, idx: i64) -> Type #builtin;
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// --- Reify'd shapes built in sx library code (no new compiler machinery) ---
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//
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// The channel result types, expressed as type-fns over `reify`. They are the
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// canonical demonstration that `reify` carries a full enum through codegen:
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// `RecvResult(i64)` constructs and matches like any hand-written enum, and is
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// one nominal type across sites (the type-fn mangled-name identity path). The
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// channel library (N3) consumes these once it lands.
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// A blocking recv: a value, or the channel was closed (drained).
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RecvResult :: ($T: Type) -> Type {
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return reify(.enum(.{ variants = .[
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EnumVariant.{ name = "value", payload = T },
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EnumVariant.{ name = "closed", payload = void },
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] }));
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}
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// A non-blocking try-recv: a value, currently empty, or closed — three states
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// a bool can't express.
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TryResult :: ($T: Type) -> Type {
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return reify(.enum(.{ variants = .[
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EnumVariant.{ name = "value", payload = T },
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EnumVariant.{ name = "empty", payload = void },
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EnumVariant.{ name = "closed", payload = void },
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] }));
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}
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