// Variadic heterogeneous type packs — step 3: `$args[$i]` in
// type positions.
//
// `$args[$i]` resolves to the i-th element type of the active
// pack binding wherever a type expression is expected:
// - return type: `-> $args[0]`
// - local var annotation: `x : $args[1] = ...`
// - (later: param types, fn-pointer types, struct field types)
//
// Today's parser hits "expected '{'" at the `$args[0]` token in
// the return type position because the `$<ident>` arm only
// accepts plain generic names; `[<int>]` after the name isn't
// recognised. This file pins that rejection. Next commit teaches
// the parser to accept `$<pack>[<int>]` and adds a new
// `PackIndexTypeExpr` AST node; `resolveTypeWithBindings`
// consults the active `pack_arg_types` map.
//
// The body intentionally exercises TWO positions per mono — the
// return type AND a local annotation — so the parser change has
// to cover more than just the trailing return arrow.

#import "modules/std.sx";

swap_take :: (..$args) -> $args[0] {
    second : $args[1] = args[1];
    // `second` is bound and typed — confirms the local-annotation
    // path also resolves. The body returns args[0] (statically
    // typed as $args[0]).
    return args[0];
}

main :: () -> s32 {
    // Heterogeneous call shapes — each picks a different concrete
    // pair, gets its own mono.
    a : s64 = swap_take(42, "ignored");      // $args[0] = s64, $args[1] = string
    b : string = swap_take("first", 99);      // $args[0] = string, $args[1] = s64
    print("{} {}\n", a, b);
    return 0;
}
