https://github.com/mfellner/typelens

Work in progress.
https://github.com/mfellner/typelens

Last synced: 3 months ago
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Work in progress.

• Host: GitHub
• URL: https://github.com/mfellner/typelens
• Owner: mfellner
• License: mit
• Created: 2018-03-08T16:38:59.000Z (over 7 years ago)
• Default Branch: master
• Last Pushed: 2018-04-05T14:55:20.000Z (about 7 years ago)
• Last Synced: 2024-10-12T00:24:14.604Z (8 months ago)
• Language: TypeScript
• Homepage:
• Size: 86.9 KB
• Stars: 0
• Watchers: 0
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# TypeLens

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**TypeLens** is a typesafe lensing library for JavaScript and TypeScript.

### Introduction

TypeLens is inspired by and borrows ideas from [Ramda](http://ramdajs.com/docs/#lens) and [Fantasy Land](https://github.com/fantasyland/fantasy-land). It is made to **safely access** properties in **unknown objects**.

### Usage

```typescript

import { lensKey } from 'typelens';

// Fetch some unsafe data.

const data = await fetch(url).then(r => t.json());

// Define a lens for a nested property.

const nameLens = lensKey(['user', 'profile', 'name']);

// Read the value at the focused property using `view`.

// Accessing a value with a lens returns a `Maybe` type.

const nameMaybe = lensKey.view(data);

// Safely resolve the value to a string. If the value is

// undefined, 'anonymous' used used as fallback.

const name: string = nameMaybe.getString('anonymous');

```

### Articles on functional lenses

* [Basic Lensing](https://www.schoolofhaskell.com/school/to-infinity-and-beyond/pick-of-the-week/basic-lensing)

* [Taking a Closer Look at Lenses](https://hackernoon.com/taking-a-closer-look-at-lenses-c0304851d54c)

* [Functional Lenses, How Do They Work](https://medium.com/@dtipson/functional-lenses-d1aba9e52254)