Pipeline operator in Ruby

pipeline-operator.rb

# mul_x_y :: [Fixnum, Fixnum] -> Fixnum
mul_x_y = ->(x, y) { x * y }

# adder :: Fixnum -> (Fixnum -> Fixnum)
adder = ->(base) {
  ->(input) { input + base }
}

# add_two :: Fixnum -> Fixnum
add_two = adder[2]

# mul_add :: [Fixnum, Fixnum] -> String
mul_add = (mul_x_y |> add_two)

p mul_x_y[2, 3]              # => 6
p add_two[2]                 # => 4
p mul_add[2, 3]              # => 8
p (mul_add.
   |> adder[2].
   |> (->(x) { [x-1, x+1] })
  )[2, 3]                    # => [9, 11]