https://github.com/purescript/purescript-refs

Mutable value references
https://github.com/purescript/purescript-refs

Last synced: 21 days ago
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Mutable value references

• Host: GitHub
• URL: https://github.com/purescript/purescript-refs
• Owner: purescript
• License: bsd-3-clause
• Created: 2014-03-19T22:12:38.000Z (almost 12 years ago)
• Default Branch: master
• Last Pushed: 2022-04-27T14:20:50.000Z (almost 4 years ago)
• Last Synced: 2025-11-30T04:48:18.933Z (3 months ago)
• Language: PureScript
• Homepage:
• Size: 56.6 KB
• Stars: 21
• Watchers: 5
• Forks: 21
• Open Issues: 1
• Metadata Files:
  • Readme: README.md
  • Changelog: CHANGELOG.md
  • License: LICENSE

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README

          
# purescript-refs

[![Latest release](http://img.shields.io/github/release/purescript/purescript-refs.svg)](https://github.com/purescript/purescript-refs/releases)

[![Build status](https://github.com/purescript/purescript-refs/workflows/CI/badge.svg?branch=master)](https://github.com/purescript/purescript-refs/actions?query=workflow%3ACI+branch%3Amaster)

[![Pursuit](https://pursuit.purescript.org/packages/purescript-refs/badge)](https://pursuit.purescript.org/packages/purescript-refs)

This module defines functions for working with mutable value references.

_Note_: [`Control.Monad.ST`](https://pursuit.purescript.org/packages/purescript-st/4.0.0/docs/Control.Monad.ST) provides a _safe_ alternative to `Ref` when mutation is restricted to a local scope.

## Installation

```

spago install refs

```

## Example

```purs

import Effect.Ref as Ref

main = do

  -- initialize a new Ref with the value 0

  ref <- Ref.new 0

  -- read from it and check it

  curr1 <- Ref.read ref

  assertEqual { actual: curr1, expected: 0 }

  -- write over the ref with 1

  Ref.write 1 ref

  -- now it is 1 when we read out the value

  curr2 <- Ref.read ref

  assertEqual { actual: curr2, expected: 1 }

  -- modify it by adding 1 to the current state

  Ref.modify_ (\s -> s + 1) ref

  -- now it is 2 when we read out the value

  curr3 <- Ref.read ref

  assertEqual { actual: curr3, expected: 2 }

```

See [tests](test/Main.purs) to see usages.

## Documentation

Module documentation is [published on Pursuit](http://pursuit.purescript.org/packages/purescript-refs).