ncurry/index.js

Curry for named arguments

'use strict'

function curryNamed (keys, fn) {
  return function helper (cache) {
    return function (...objects) {
      const incoming = Object.assign({}, ...objects)
      const argsOverridden = includesSome(Object.keys(cache), Object.keys(incoming))
      const error = `The following arguments were overidden: ${argsOverridden}`
      if (argsOverridden.length > 0) throw Error(error)
      const obj = Object.assign({}, cache, ...objects)
      return includesEvery(keys, Object.keys(obj)) ? fn(obj) : helper(obj)
    }
  }({})
}

const includesEvery = (mandatory, received) =>
  mandatory.every(key =>
    received.includes(key))

const includesSome = (mandatory, received) =>
  mandatory.filter(key =>
    received.includes(key))

module.exports = curryNamed