7a9db03bcc
declare now takes the type's NAME — `declare(name) -> Type` — because the
compiler needs it at compile time to register the forward type, which is
what makes self-reference resolve. EnumInfo drops `name` (it lives on
declare now); define completes the handle's body in place (the slot is
already named).
Self-reference mechanism (evalComptimeType): before lowering a comptime
type expression, preregisterForwardTypes scans it (and a called ctor fn's
body) for `declare("Name")` calls and registers each as an empty forward
nominal type AND binds it as a type alias. The alias is essential: a
`Name :: ctor()` decl makes `Name` a const_decl author, so a `*Name`
self-reference resolves through the forward-ALIAS path
(type_aliases_by_source), which a bare findByName registration doesn't
satisfy. With both in place `*Name` resolves to the forward slot at lower
time; the interp's declare returns that same slot; define fills it.
List :: make_list();
make_list :: () -> Type {
h := declare("List");
return define(h, .enum(.{ variants = .[
EnumVariant.{ name = "cons", payload = *List },
EnumVariant.{ name = "nil", payload = void } ] }));
}
Verified: cons/nil construct + match (direct and through the pointer),
multi-node list traversal via a recursive `count(*List)`. meta.sx
RecvResult/TryResult + examples 0614/0615/0617 updated to declare(name);
full suite green (673).
31 lines
1.0 KiB
Plaintext
31 lines
1.0 KiB
Plaintext
// Comptime type construction: mint a NEW nominal enum from a `TypeInfo` value
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// via the `define(declare("E"), info)` primitives, then construct one of its
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// variants and match on it — exercising that a programmatically-built enum
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// (with NO backing AST decl) flows through enum codegen unmodified (layout /
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// construct / match), byte-identical to a hand-written enum.
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//
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// The enum has two variants: `value` carrying an i64 payload, and `closed` with
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// no payload (`payload = void`).
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#import "modules/std.sx";
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#import "modules/std/meta.sx";
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E :: define(declare("E"), .enum(.{ variants = .[
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EnumVariant.{ name = "value", payload = i64 },
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EnumVariant.{ name = "closed", payload = void },
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] }));
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main :: () -> i32 {
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e := E.value(3);
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if e == {
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case .value: (v) { print("value {}\n", v); }
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case .closed: { print("closed\n"); }
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}
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c : E = .closed;
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if c == {
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case .value: (v) { print("value {}\n", v); }
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case .closed: { print("closed\n"); }
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}
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return 0;
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}
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