A C enum

# A C enum (owner, 2026-09-27: a): `layout.C enum`, a number per case as the C header
# gives it, no data. It is a Zag enum in every other way — `match` covers every
# case, and it is owned like every enum (2026-09-20) — and C-shaped, so `extern.C fn`
# can take and return it. A number C hands back that no case has fails `out_of_range`.
layout.C enum Key { a = 65, b = 66, escape = 256 }
extern.C fn IsKeyDown ['key': Key] -> bool;

fn name ['k': Key] -> str.utf8 {
    match 'k' {
        a { return "A"; }
        b { return "B"; }
        escape { return "Esc"; }
    }
}

MAIN {
    let 'k' := Key.escape;
    std::print.useful[name[copy 'k'], " ", name[Key.a], newln];
}