sub the_function(Range $a, Range $b, $s) {
  my ($a1, $a2) = $a.bounds;
  my ($b1, $b2) = $b.bounds;
  return $b1 + (($s-$a1) * ($b2-$b1) / ($a2-$a1));
}

for ^11 -> $x { say "$x maps to {the_function(0..10, -1..0, $x)}" }