humanhighway · February 7, 2021 09:40
diff --git a/box-example.js b/box-example.js
 const Box = (x) => ({
  map: f => Box(f(x)),  // always return Box type.
  fold: (f) => f(x), // unwarp value
 })

 const result= Box(10)
  .map((x) => x * 2)
  .map((x) => x + 10)
  .fold(x => x);

 console.log(result);
	const Box = (x) => ({
	map: f => Box(f(x)), // always return Box type.
	fold: (f) => f(x), // unwarp value
	})

	const result= Box(10)
	.map((x) => x * 2)
	.map((x) => x + 10)
	.fold(x => x);

	console.log(result);