# @pedromsilva/data-either

> Simple TypeScript/ES2017 class to represent either values

Latest version **0.0.2** (published 2018-04-25) · ISC license · 0 weekly downloads

## Install

```sh
npm install @pedromsilva/data-either
pnpm add @pedromsilva/data-either
yarn add @pedromsilva/data-either
bun add @pedromsilva/data-either
```

## Health

**Score 25/100 (F)** — status: abandoned.

Positive: has types; no vulnerabilities; high quality score.

Warnings: low downloads; no esm support; pre 1.0.

Negative: abandoned; low maintenance score.

## Facts

| | |
|---|---|
| Version | 0.0.2 |
| Published | 2018-04-25 |
| First published | 2018-04-19 |
| Weekly downloads | 0 |
| License | ISC |
| TypeScript types | bundled |
| Module format | CommonJS |
| Dependencies | 0 |
| Unpacked size | 28.2 KB |
| Known vulnerabilities | 0 |
| Install scripts | no |
| GitHub stars | 0 |
| Author | Pedro M. Silva |
| Maintainers | pedromsilva |
| Keywords | js, immutable, either, monadic, data, values, container |

## Links

- npm: https://www.npmjs.com/package/@pedromsilva/data-either
- Repository: https://github.com/pedromsilvapt/data-either
- Homepage: https://github.com/pedromsilvapt/data-either#readme
- Issues: https://github.com/pedromsilvapt/data-either/issues
- npm.io page: https://npm.io/package/@pedromsilva/data-either

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## Recent versions

- 0.0.2 (latest) — 2018-04-25
- 0.0.1 — 2018-04-19

## README

# Either

> Simple TypeScript/ES2017 class to represent either values

# Installation
```shell
npm install --save data-either
```

# Usage
```typescript
import { Either } from 'data-either';

const left = Either.left( 1 );
const right = Either.right( 20 );

left.isRight(); // false
right.isRight(); // true
```

You can also convert trowable functions into either.
```typescript
import { Either } from 'data-either';

const left = Either.ofThrowable( () => 2 );
const right = Either.ofThrowable( () => { throw new Error(); } );

left.getLeft(); // 2
right.getRight(); // Error
```

Convert a Promise that can reject into an always resolved promise.
```typescript
import { Either } from 'data-either';

const left = Either.ofPromise( Promise.resolve( "left" ) );
const right = Either.ofPromise( Promise.reject( new Error() ) );

left.getLeft(); // "left"
right.getRight(); // Error
```

There are also a number of computations that can be done functionally with this module.
```typescript
import { Either } from 'data-either';

let value : Either<number, string> = Either.left( 1 );

value = value.map( n => n * 3, err => `Error: ${ err }` ); // Either.left( 3 )

value = value.flatMap( n => n % 2 === 0 ? Either.left( n ) : Either.right( "Error: Not event." ), r => Either.right( r ) ); // Either.right( "Error: Not even." )
// Or simply
value = value.flatMapLeft( n => n % 2 === 0 ? Either.left( n ) : Either.right( "Error: Not event." ) ); // Either.right( "Error: Not even." )

value.leftOrElse( 0 ); // 0
```

---
_Source: https://npm.io/package/@pedromsilva/data-either · Machine-readable twin of the npm.io package page. Health data is recomputed on every publish._