442a70b8c9
First slice of the re-architecture. The compiler gains two comptime
type-construction builtins — declare() (mint an empty/undefined nominal
slot) and define(handle, info) (decode a TypeInfo VALUE + complete the
slot) — executed by the interpreter against a new `mint` TypeTable handle
(setMintTable). reify becomes PLAIN sx in meta.sx:
reify :: (info) -> Type { h := declare(); define(h, info); return h; }
`E :: f(...)` where f is a non-generic Type-returning fn (reify, and later
make_enum) is now comptime-evaluated via evalComptimeTypeNamed: wrap the
call in a throwaway comptime fn, run it through the interp with the mint
table enabled so declare/define mint the type, read back the type_tag, and
rename the anonymous slot to the binding name. The compiler has ZERO reify
knowledge at the decl site — the old `E :: reify` hook is deleted.
examples/0614 (inline reify) now runs on this floor. Full suite green (673).
INTERMEDIATE: reifyType + findReturnReifyCall still serve the type-fn path
(0615/0617) and will be deleted in the next slice (type-fn body
comptime-eval), after which the compiler has no reify code at all.
79 lines
3.4 KiB
Plaintext
79 lines
3.4 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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// The compiler's ONLY type-construction primitives (comptime-only #builtins):
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// declare() — mint a NEW empty (undefined) nominal type, returned
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// as a `Type` handle. Using it before `define` is a
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// loud error. References to it (`*Self`) are fine.
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// define(handle, info) — fill a declared handle's body from a `TypeInfo`.
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// `reify` and every other constructor below are PLAIN sx built over these — the
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// compiler has no `reify` knowledge.
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declare :: () -> Type #builtin;
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define :: (handle: Type, info: TypeInfo) #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(info) — the one-shot, non-recursive sugar: declare + define + return.
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// (Recursive / mutually-recursive types use the explicit declare/define split
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// so the handle can be referenced inside its own definition.)
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reify :: (info: TypeInfo) -> Type {
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h := declare();
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define(h, info);
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return h;
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}
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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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