moy-fp/src/Functor/join.js

A functional programming library.

import curry from '../Function/curry'

/**
 * Functor f => f (f a) -> f a
 */
const join = curry(
  F => Object.prototype.toString.call(F) === '[object Array]' ?
    F.reduce(
      (acc, cur) => acc.concat(cur),
      [],
    ):
    F.join()
)

export default join