Generic function composition in Swift

gistfile1.swift

@infix func * <A,B,C> (g: B -> C, f: A -> B) -> (A) -> C {
  return {(x: A) -> C in
    return g(f(x))
  }
}

var f = {(x: Int) -> Float in
  return Float(x * x) / 2.0
}

var g = {(x: Float) -> Float in
  return 1.0 / x
}

(atanf * g * f)(3)