bd139dc09c
REIFY Phase 2.0. Add examples/0616: reflect a struct's fields (name via
field_name, type via field_type) and a tagged-union's variant payloads,
including field_type composed inside type_eq / type_name. Seed an empty
expected/*.exit marker. RED by design — field_type still bails ("not yet
implemented"); Phase 2.1 implements it over the type table and turns
this green.
30 lines
1.4 KiB
Plaintext
30 lines
1.4 KiB
Plaintext
// REIFY Phase 2: `field_type($T, i) -> Type` — the type-only field projection
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// the value-level reflection (`field_value` / `type_of`) couldn't express.
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// Reflect a struct's fields by name (`field_name`) AND by type (`field_type`),
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// and a tagged-union's variant payloads. It folds at lower time, so it composes
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// inside `type_eq` / `type_name` / any type-arg slot.
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#import "modules/std.sx";
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#import "modules/std/meta.sx";
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Point :: struct { x: i64; y: f64; on: bool; }
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Msg :: enum { num: i64; tag: bool; quit; }
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main :: () -> i32 {
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// Struct fields: name + type, position by position.
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print("Point has {} fields\n", field_count(Point));
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print(" 0: {} : {}\n", field_name(Point, 0), type_name(field_type(Point, 0)));
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print(" 1: {} : {}\n", field_name(Point, 1), type_name(field_type(Point, 1)));
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print(" 2: {} : {}\n", field_name(Point, 2), type_name(field_type(Point, 2)));
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// field_type composes in a type-arg slot (type_eq folds at comptime).
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print("field 0 is i64: {}\n", type_eq(field_type(Point, 0), i64));
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print("field 1 is f64: {}\n", type_eq(field_type(Point, 1), f64));
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// Tagged-union variant payloads (the tagless `quit` → void).
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print("Msg.num payload: {}\n", type_name(field_type(Msg, 0)));
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print("Msg.tag payload: {}\n", type_name(field_type(Msg, 1)));
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print("Msg.quit payload: {}\n", type_name(field_type(Msg, 2)));
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return 0;
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}
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