class Proc
      def self.compose(f, g)
        lambda { |*args| f[g[*args]] }
      end
      def *(g)
        Proc.compose(self, g)
      end
    end

    inc    = lambda { |x| x + 1 }
    thrice = lambda { |x| 3 * x }

    thrice_of_inc = thrice * inc
    thrice_of_inc[1]
    => 6

    twice_of_dec  = lambda { |x| 2 * x } * lambda { |x| x - 1 }
    twice_of_dec[3]
    => 4

    thrice_of_inc_of_thrice = thrice * inc * thrice
    thrice_of_inc_of_thrice[1]
    => 12

It almost feels as if it were meant to be that way. ;-)
I love Ruby.