type-option.js

const three = {
  type: () => [Integer],
  value: 3
}

const three = {
  type: () => [Integer],
  value: 3
}

const sum = {
  type: () => [Arrow, [Tuple, Integer, Integer], Integer],
  value: (x, y) => x + y
}

const threeAndFour = {
  type: () => [Tuple, Integer, Integer],
  value: [three, four]
}

eq(
  sum.ap(threeAndFour),
  {
    type: () => [Integer],
    value: 7
  }
)

const Arrow = {
  type: (a, b) => [Type, a, b],
  value: {
    ap: {
      type: a => [Arrow, a, a],
      value: self => argument => self(argument)
    },
    pipe: {
      type: (a, b) => [Arrow, a, b]
      value: self => argument => other => self(argument(other))
    }
  }
}