043 pairwise other readonly

// TEST: kernel:pairwise with read-only k.other (correct form)
//
// Each element k reads from k.other (all other elements) and writes only
// to itself. The transform guarantees non-aliasing:
//   - self: noalias *Body       (writable, unique)
//   - other: noalias *const Body (read-only, unique)
//
// This is the form that maps to GPU: each "thread" is one element,
// reads all others, writes only to itself.

~import "$std/kernel"
~import "$std/io"

~std.kernel:shape(Body) {
    mass: f64,
}

~std.kernel:init(Body) {
    { mass: 1.0 },
    { mass: 2.0 },
    { mass: 3.0 },
}
| kernel k |>
    std.kernel:pairwise {
        k.mass += k.other.mass
    }

~std.io:print.ln("pairwise complete")