moy-fp/src/Functor/maybe.js

A functional programming library.

import curry from '../Function/curry'

/**
 * Maybe m => b -> (a -> b) -> m a -> b
 */
const maybe = curry(
  (value, fn, m) => {
    if(m.value === null || m.value === undefined){
      return value
    }
    return fn(m.value)
  }
)

export default maybe