@isthmus/optics

This is a small set of optics for modifying objects in an immutable fashion.

Installation

You can install _@isthmus/optics with:

npm install --save @isthmus/optics

Then to use in your JavaScript:

import { set, view, over } from '@isthmus/atom'

// and then use...

There is a umd version available under @isthmus/optics/dist/optics.js:

<script src="https//unpkg.com/@isthmus/optics/dist/optics.js"></script>
<script>
  const { set, view, over } = isthmusOptics
  // ...
</script>

API

Note that all functions without optional arguments are curried with crry.

• set
• view
• over

set

set(lens, value, target) -> result

set is a function which takes a lens (string, number, or array), value, and object or array. It makes the adjustment and returns the result.
The original target is not modified.

const obj = { a: 'foo', b: [1, 2, 3] }
const arr = [1, 2, 3]

set('a', 'bar', obj) // { a: 'bar', b: [1, 2, 3] }
set(1, 7, arr) // [1, 7, 3]
set(['b', 1], 11, obj) // { a: 'foo', b: [1, 11, 3] }

view

view(lens, target) -> result

view is a function which takes a lens and target. It returns the result if it is found, or undefined otherwise.

const obj = { a: 'foo', b: [1, 2, 3] }

view('a', obj) // 'foo'
view(['b', 1], obj) // 2
view(['c', 7, 'd'], obj) // undefined

over

over(lens, transform, target) -> result

over is a function which takes a lens, transform function, and object. It adjusts the target based on the given transform, and returns the result.
The original target is not modified.

const obj = { a: 'foo', b: [1, 2, 3] }

over(['b', 1], x => x * x, obj) // { a: 'foo', b: [1, 4, 3] }