Functional programming: pipe forward and forward composition

Operators.swift

func incr(_ x: Int) -> Int {
  return x + 1
}

func square(_ x: Int) -> Int {
  return x * x
}

precedencegroup ForwardApplication {
  associativity: left
}

infix operator |>: ForwardApplication

func |> <A, B>(x: A, f: (A) -> B) -> B {
  return f(x)
}

2 |> incr |> square

precedencegroup ForwardComposition {
  higherThan: ForwardApplication
  associativity: left
}
infix operator >>>: ForwardComposition

func >>> <A, B, C>(_ f: @escaping (A) -> B, _ g: @escaping (B) -> C) -> ((A) -> C) {
  return { a in g(f(a)) }
}

2 |> incr >>> square

[1, 2, 3]
  .map(square)
  .map(incr)

[1, 2, 3]
  .map(square >>> incr)