012 for binding in nested range

// TEST: For loop binding used in nested range expression
//
// VERIFIES: Range-based for bindings (i, j) are direct values, NOT wrapped.
// Use: for(i+1..5) NOT for(i.val+1..5)
//
// This pattern iterates over pairs where j > i

const std = @import("std");

~import std/control

~event print-pair { i: usize, j: usize }

~proc print-pair|zig {
    std.debug.print("{},{}\n", .{i, j});
}

// This pattern: for(0..3) | each i |> for(i+1..5)
// Should iterate over pairs (0,1), (0,2), (0,3), (0,4), (1,2), (1,3), (1,4), (2,3), (2,4)
~for(0..3)
! each i |> for(i+1..5)
    ! each j |> print-pair(i, j)
| done |> _