vector_add.mapal

// vector_add.mapal — elementwise add of two fixed-size i32 vectors, via `zip`.
//
// Historical note (pre-ADR-0018): Core had no `zip` and `map` is unary with a
// non-capturing body (L1108), so a zipWith had to be written as an unrolled array
// literal — one `a[k] + b[k]` per slot, monomorphic in (T, n). ADR-0018 added the
// `zip` / `enumerate` builtins, so the elementwise add is now the generic-shaped
// `(a, b) -> zip -> map { p -> p.0 + p.1 }`.

fn main() {
    // a = [0, 1, 2, …, 15],  b = [100, …, 100]   ⇒   c[k] = k + 100
    [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15]    -> a: [i32; 16];
    [100, 100, 100, 100, 100, 100, 100, 100,
     100, 100, 100, 100, 100, 100, 100, 100]                  -> b: [i32; 16];

    (a, b) -> zip -> map { p -> p.0 + p.1 } -> c: [i32; 16];

    // Arrays are not printable, so show a few slots and the total.
    "c[0]  = " -> print;   c[0]  -> println;   // expect 100
    "c[15] = " -> print;   c[15] -> println;   // expect 115

    "sum   = " -> print;                       // expect (0+…+15) + 16*100 = 1720
    (0, c) -> fold { acc, x -> acc + x } -> total;
    total -> println;
}