Bitmask.js

// Slick little method to create a bitmask from an array of boolean values. (for Javascript)
function bitMask(a, b) {
    var m = 0, i;
    
    if (b !== undefined) { a = Array.prototype.slice.apply(arguments); }
    
    for (i = 0; i < a.length; i += 1) {
	if (a[i] !== false) { m += Math.pow(2, i) };
    }
    return m;
}

Bitmask.rb

# Slick little method to create a bitmask from an array of boolean values. (for Ruby)
def bitMask a
  n = -1
  b = a.map { |x| 2**(n+=1) * (x ? 1 : 0) }
  b.inject { |s, x| s += x }
end