https://github.com/kylecorbelli/typescript-maybe

A TypeScript Maybe Type and Module
https://github.com/kylecorbelli/typescript-maybe

elm elm-lang functional-programming haskell javascript maybe maybe-monad typescript

Last synced: about 1 month ago
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A TypeScript Maybe Type and Module

• Host: GitHub
• URL: https://github.com/kylecorbelli/typescript-maybe
• Owner: kylecorbelli
• Created: 2018-05-02T23:35:09.000Z (over 6 years ago)
• Default Branch: master
• Last Pushed: 2018-05-05T18:04:48.000Z (over 6 years ago)
• Last Synced: 2024-11-14T16:55:43.679Z (about 1 month ago)
• Topics: elm, elm-lang, functional-programming, haskell, javascript, maybe, maybe-monad, typescript
• Language: TypeScript
• Homepage: http://kylecorbelli.com/index.php/2018/05/01/typescript-maybe-type-module/
• Size: 51.8 KB
• Stars: 3
• Watchers: 2
• Forks: 2
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

        
# TypeScript Maybe Type and Module

## Installation

```

$ npm install --save typescript-maybe

```

## Example Usage

```TypeScript

import { Maybe, MaybeType } from 'typescript-maybe'

import { compose, toUpper } from 'ramda'

// An example of an "unsafe" function that may return undefined or null:

function unsafeHead (list: ReadonlyArray): T {

  return list[0]

}

// Elegantly handling this unsafe function in a composition chain:

type UpperCaseHead = (list: ReadonlyArray) => Maybe

const otherUpperCaseHead: UpperCaseHead = compose(

  Maybe.map(toUpper),

  Maybe.of(unsafeHead),

) as UpperCaseHead

// Handling Maybe in a composition chain and returning a default value:

type UpperCaseHeadWithDefault = (list: ReadonlyArray) => string

const upperCaseHeadWithDefault: UpperCaseHead = compose(

  Maybe.withDefault('Something didn’t quite go according to plan!'),

  Maybe.map(toUpper),

  Maybe.of(unsafeHead),

) as UpperCaseHeadWithDefault

```