Functional Snake Game - Part 2 - Input

index.js and snake.js

// index.js
const setupInput = () => {
  readline.emitKeypressEvents(process.stdin)
  process.stdin.setRawMode(true)
  process.stdin.on("keypress", (str, key) => {
    if (key.ctrl && key.name === "c") process.exit()

    const options = {
      UP: addMove(direction.NORTH),
      LEFT: addMove(direction.WEST),
      DOWN: addMove(direction.SOUTH),
      RIGHT: addMove(direction.EAST),
    }

    const move = options[key.name.toUpperCase()]
    uglyMutableState = move(uglyMutableState)
  })
}

// snake.js
const direction = {
  NORTH: point(0, -1),
  SOUTH: point(0, 1),
  WEST: point(-1, 0),
  EAST: point(1, 0),
}

const initialState = {
  snake: [point(4, 3)],
  apple: point(5, 5),
  move: direction.EAST,
}

const addMove = r.curry((direction, state) =>
  isValidMove(direction, state.move) ? { ...state, move: direction } : state
)

// Comprueba que la serpiente siempre se mueve hacia adelante y
// no pueda cambiar a la dirección opuesta
const isValidMove = (direction, move) =>
  direction.x + move.x !== 0 && direction.y + move.y !== 0