// Range-based for loops: `for start..end (i) { }` (cursor optional, `end`
// exclusive) is a runtime counting loop; `inline for start..end (i) { }`
// is comptime-unrolled — the cursor is a compile-time constant each
// iteration, so `xs[i]` over a heterogeneous pack substitutes the concrete
// per-position element (this is what drives pack iteration).

#import "modules/std.sx";

Show :: protocol {
    show :: () -> string;
}
A :: struct { x: s64; }
B :: struct { s: string; }
impl Show for A { show :: (self: *A) -> string => "A"; }
impl Show for B { show :: (self: *B) -> string => "B"; }

// Comptime-unrolled iteration over a pack; cursor `i` indexes the pack.
each :: (..xs: Show) -> void {
    inline for 0..xs.len (i) {
        print("[{}]={}\n", i, xs[i].show());
    }
}

main :: () -> s32 {
    // Runtime range, cursor used.
    for 0..3 (i) { print("i={}\n", i); }

    // Runtime range, no cursor — body runs `end - start` times.
    n := 0;
    for 0..5 { n = n + 1; }
    print("n={}\n", n);

    // Non-zero start.
    for 2..5 (j) { print("j={}\n", j); }

    // Inline unroll over a heterogeneous pack.
    each(A.{ x = 1 }, B.{ s = "hi" }, A.{ x = 3 });
    0
}