// `inline for` element form over a pack — multi-iterable parity with the
// runtime for-loop. Position 0 drives the unroll count (a pack's arity or a
// bounded range's span); trailing iterables pair with it. A pack capture is
// the concrete per-position element viewed through the constraint protocol
// (same semantics as `xs[i]`); a range capture is a comptime cursor.
//
//   inline for xs (x)            — element form
//   inline for xs, 0.. (x, i)    — element + paired index
//   inline for 0..xs.len, xs (i, x) — range driver, trailing pack
//   inline for xs { }            — captureless; N=0 unrolls nothing

#import "modules/std.sx";

Show :: protocol { show :: () -> string; }
IntBox :: struct { v: i64; }
StrBox :: struct { s: string; }
impl Show for IntBox { show :: (self: *IntBox) -> string { int_to_string(self.v) } }
impl Show for StrBox { show :: (self: *StrBox) -> string { self.s } }

bare :: (..xs: Show) {
    inline for xs (x) {
        print("bare: {}\n", x.show());
    }
}
elem_and_index :: (..xs: Show) {
    inline for xs, 0.. (x, i) {
        print("{}: {}\n", i, x.show());
    }
}
range_driver :: (..xs: Show) {
    inline for 0..xs.len, xs (i, x) {
        print("r{}: {}\n", i, x.show());
    }
}
offset_index :: (..xs: Show) {
    inline for xs, 10.. (x, i) {
        print("{} -> {}\n", i, x.show());
    }
}
captureless :: (..xs: Show) {
    n := 0;
    inline for xs { n += 1; }
    print("ran {}\n", n);
}
value_pos :: (..xs: Show) {
    inline for xs (x) {
        print("val: {}\n", x);
    }
}
empty :: (..xs: Show) {
    inline for xs (x) { print("never\n"); }
    print("empty ok\n");
}

main :: () {
    bare(IntBox.{ v = 7 }, StrBox.{ s = "hi" });
    elem_and_index(IntBox.{ v = 7 }, StrBox.{ s = "hi" });
    range_driver(IntBox.{ v = 1 }, StrBox.{ s = "two" });
    offset_index(StrBox.{ s = "x" }, StrBox.{ s = "y" });
    captureless(IntBox.{ v = 0 }, IntBox.{ v = 0 }, IntBox.{ v = 0 });
    value_pos(IntBox.{ v = 42 });
    empty();
}