Functional Ambient in JS

ambient.js

function bind(ambient, name, value) {
  return function lookup(n) {
    if(n == name) {
      return value
    } else {
      return ambient(n)
    }
  }
}

function generateAmbient() {
  return bind(() => void 0)
}

const defaultAmbient = generateAmbient()
ambient1 = bind(defaultAmbient, "x", 5)
ambient2 = bind(ambient1, "y", 7)
ambient3 = bind(ambient2, "z", 4)

ambient3("x") // 5
ambient3("y") // 7
ambient3("z") // 4
ambient3("w") // undefined