#!/usr/bin/ruby
#
## http://rosettacode.org/wiki/Generator/Exponential#Sidef
#
func gen_pow(m) {
    var e = 0
    func { e++ ** m }
}
  
func gen_filter(g1, g2) {
    var v2 = g2.run
    func {
        loop {
            var v1 = g1.run
            while (v1 > v2) { v2 = g2.run }
            v1 == v2 || return v1
        }
    }
}
  
# Create generators.
var squares = gen_pow(2)
var cubes = gen_pow(3)
var squares_without_cubes = gen_filter(squares, cubes)
  
# Drop 20 values.
{ squares_without_cubes() } * 20
  
# Print 10 values.
var answer = []
{ answer.append(squares_without_cubes()) } * 10
say answer
assert_eq(answer, [529, 576, 625, 676, 784, 841, 900, 961, 1024, 1089]);