The option monad example might be closer. I'm having trouble figuring out how to get the value out of it though

       data Option a =
	  Some a | None

        let optionMonad = {
		return: fn x =
		Some x
	  bind: fn x f = match x
		case (Some a) = f a
		case None = None
	}

	let m = (do optionMonad
	  bind x = Some 1
	  let y = 2
	  bind z = Some 3
	  return x + y + z
	)

	match m 
		case (Some x) = console.log x

shows an error Error: Type error: Native is not Option 'dwk