Skip to content
master
Switch branches/tags
Code

Latest commit

 

Git stats

Files

Permalink
Failed to load latest commit information.
Type
Name
Latest commit message
Commit time
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

tsoption Build Status npm mit fantasy

Correct, easy to use Option type for TypeScript. Like Scala options; see the introductory blog post.

Installation

# Using Yarn:
yarn add tsoption

# Or, using NPM:
npm install tsoption --save

Usage

Note: You can use JavaScript instead of TypeScript, but it's not as fun.

let a = Option.of(3)                  // Some<number>(3)
  .flatMap(_ => Some.of(5))           // Some<number>(5)
  .map(_ => 'a')                      // Some<string>('a')
  .orElse(Option.of('b'))             // Some<string>('a')   (non-string type gives a compile error)
  .getOrElse('c')                     // 'a'

let b = Option.of('a')                // Some<string>('a')
  .flatMap(_ => new None)             // None<string>()      (flatMap can map to any type)
  .orElse(Option.of('b'))             // Some<string>('b')   (non-string type gives a compile error)
  .get()                              // 'b'

API

Note: The types of each of the expressions below are known at compile time.

// Create an option
Option.of(3)                            // Some(3)
Option.of('abc')                        // Some('abc')
Option.of(null)                         // None                (for convenience)
Option.of(undefined)                    // None                (for convenience)
Some.of(3)                              // Some(3)
Some.of(null)                           // Some(null)
new Some([1, 2, 3])                     // Some([1, 2, 3])
new None                                // None

// #flatMap
Some.of(3).flatMap(_ => Some.of(_ * 2)) // Some(6)
None.of().flatMap(() => Some.of(2))     // None

// #get
Some.of(3).get()                        // 3
None.of().get()                         // COMPILE ERROR! Can't call get() on None

// #getOrElse
Some.of(1).getOrElse(2)                 // 1
None.of().getOrElse(2)                  // 2

// #isEmpty
Some.of(2).isEmpty()                    // false (known at compile time too!)
None.of().isEmpty()                     // true (known at compile time too!)

// #map
Some.of(2).map(_ => _ * 2)              // Some(4)
None.of().map(() => 2)                  // None (known at compile time too!)

// #nonEmpty
Some.of(2).nonEmpty()                   // true (known at compile time too!)
None.of().nonEmpty()                    // false (known at compile time too!)

// #orElse
Some.of(2).orElse(Option.of(3))         // Some(2)
None.of().orElse(Option.of(3))          // Some(3)

// #toString
Some.of(2).toString()                   // "Some(2)"
None.of().toString()                    // "None"

Fantasyland

TSOption is Fantasyland-compliant. It implements:

Fantasyland-Compatible API

import * as fl from 'fantasy-land'
const {ap, chain, map, of} = fl

// Create an option
Option[of](3)                           // Some(3)
Option[of]('abc')                       // Some('abc')
Option[of](null)                        // None
Option[of](undefined)                   // None

// #chain
Option[of](3)[chain](_ => Option[of](_ * 2)) // Some(6)
Option[of](null)[chain](() => Option[of](2)) // None (known at compile time too!)

// #map
Option[of](2)[map](_ => _ * 2)          // Some(4)
Option[of](null)[map](() => 2)          // None (known at compile time too!)

// #ap
Option[of](2)[ap](Option[of]((_: number) => _ * 2)) // Some(4)
Option[of](null)[ap](Option[of](() => 2)) // None (known at compile time too!)

Tests

npm test

License

MIT

About

Correct, easy to use Option type for TypeScript. πŸ¦„

Topics

Resources

Releases

No releases published

Packages

No packages published