dpath

Dot Path

FP sugar for immutables, using dot path syntax for deep property access.

Why?

Immutable.js is great, but the API is a bit awkward -- particularly the array-style path notation. These utilities provide functional programming sugar for working with the immutable.js API.

So instead of i.setIn(['a', 'b', 'c'], value); you can do set('a.b.c', i, value);.

Seems like a small thing, but with curry, you can do: const setUserRole = set('user.role', i); and then later setUserRole('enterprise'); -- which is great for repeated set calls, such as in Redux actions, for instance.

If you want to use FP pipes (lodash flow, etc...) it gets even better. Normally immutables force you out of point-free style, like this:

const pipeline = pipe(
  getImmutable,
  immutable => immutable.getIn(['a', 'b', 'c'])
  map(doSomethingWithABC)
);

With dpath, you can do this, instead, and stay point-free:

const pipeline = pipe(
  getImmutable,
  get('a.b.c')
  map(doSomethingWithABC)
);

Install

$ npm install --save dpath

dp(path: String, delimiter: String) => Array

import dp from 'dpath';
const arrPath = dp('a.b.c'); // => ['a','b','c']

// optionally specify a delimiter:
const arr2 = dp('a,b,c', ','); // => ['a','b','c']

Use with Immutable.js

import I from `immutable`;
import dp from 'dpath';

let map = I.Map().setIn(dp('a.b.c'), 'val');
map.toJS(); // => {a:{b:{c:'val'}}}

get(path: String, i: Immutable) => value: Any

Deep property get for the Immutable.js API.

const i = Immutable.fromJS({
  a: {
    b: { c: 'c' }
  }
});
get('a.b.c', i); // => 'c'

set(path: String, i: Immutable, val: Any) => Immutable

Deep property set for the Immutable.js API.

const i = Immutable.fromJS({
  a: {
    b: { c: 'c' }
  }
});
const newState = set('a.b.c', i, 23);
get('a.b.c', newState); // => 23