// Slice-of-protocol variadic `..xs: []P` — the RUNTIME counterpart to the
// comptime pack `..xs: P`. Each trailing arg is `xx`-erased to a `P` protocol
// value {ctx, vtable} and packed into a runtime `[]P`, so the elements can be
// indexed by a RUNTIME index and dispatched through the protocol interface
// (unlike a pack, which is comptime-only — see examples/163).
//
// This is the type-safe way to iterate a heterogeneous arg list at runtime:
// concrete per-position types are erased to the constraint protocol.

#import "modules/std.sx";

Show :: protocol { show :: () -> string; }
A :: struct { x: i64; }
B :: struct { s: string; }
impl Show for A { show :: (self: *A) -> string => "A"; }
impl Show for B { show :: (self: *B) -> string => "B"; }

// Runtime loop over a []Show: runtime index + protocol-method dispatch.
each :: (..xs: []Show) -> void {
    i := 0;
    while i < xs.len {
        print("[{}]={}\n", i, xs[i].show());
        i = i + 1;
    }
}

main :: () -> i32 {
    each(A.{ x = 1 }, B.{ s = "hi" }, A.{ x = 3 });   // heterogeneous, erased to Show
    each();                                            // empty is fine (len 0)
    0
}