shapeMonadExample.js

const shapeFactory  = {
  make: function () {
    console.log(arguments)
  }
}

class Monad {

  constructor ({type = undefined, scale = undefined} = {}) {
    this.type = type
    this.scale = scale
  }

  flatMap(fn) {
    return (this.scale !== undefined) ? fn(this.type, this.scale) : fn(this.type)
  }

}

const sqDef1 = new Monad({type: "square"})
const sqDef3 = new Monad({type: "square", scale: 3})

const definitions = [sqDef1, sqDef3];

const shapes = definitions.map(definition => {
  return definition.flatMap(shapeFactory.make)
});

Run with:

babel --presets ["latest"] <filename> | node