// Phase 4.2 — the canonical `Combined` struct's storage layer: a generic
// struct whose field is a pack of PARAMETERIZED-protocol values,
// `sources: (..VL(Ts))` → `(VL(T0), VL(T1), …)`. Each `VL(Ti)` is a real
// 16-byte protocol value (issue: parameterized-protocol value types), and
// `(..VL(Ts))` applies `VL` per pack element. Instantiate + whole-tuple store
// of `xx`-erased values + per-element method dispatch all work.

#import "modules/std.sx";

VL :: protocol(T: Type) { get :: () -> T; }
IntCell :: struct { v: i64; }
StrCell :: struct { s: string; }
impl VL(i64) for IntCell { get :: (self: *IntCell) -> i64 => self.v; }
impl VL(string) for StrCell { get :: (self: *StrCell) -> string => self.s; }

Combined :: struct($R: Type, ..$Ts: []Type) {
    sources: (..VL(Ts));   // (VL(T0), VL(T1), …) — tuple of protocol values
    value:   $R;
}

main :: () -> i32 {
    // Combined(i64, i64, string): R=i64, Ts=[i64, string],
    // sources: (VL(i64), VL(string)).
    c : Combined(i64, i64, string) = ---;
    c.sources = (xx IntCell.{ v = 10 }, xx StrCell.{ s = "hi" });
    c.value = 99;
    print("{} {} {}\n", c.sources.0.get(), c.sources.1.get(), c.value);  // 10 hi 99
    0
}