func map_range(a, b, x) {
    var (a1, a2, b1, b2) = (a.bounds, b.bounds);
    x-a1 * b2-b1 / a2-a1 + b1;
}

var a = 0..10;
var b = -1..0;

for x in a {
    say "#{x} maps to #{map_range(a, b, x)}";
}