https://github.com/sjoerdvisscher/effects

Control.Effects
https://github.com/sjoerdvisscher/effects

eff haskell monad-transformers

Last synced: 22 days ago
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Control.Effects

• Host: GitHub
• URL: https://github.com/sjoerdvisscher/effects
• Owner: sjoerdvisscher
• License: bsd-3-clause
• Created: 2011-10-15T19:51:45.000Z (about 13 years ago)
• Default Branch: master
• Last Pushed: 2019-04-14T14:38:14.000Z (over 5 years ago)
• Last Synced: 2024-09-15T01:48:06.279Z (about 2 months ago)
• Topics: eff, haskell, monad-transformers
• Language: Haskell
• Homepage: http://hackage.haskell.org/package/effects
• Size: 29.3 KB
• Stars: 19
• Watchers: 4
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
Control.Effects

===============

Control.Effects is a Haskell library for programming with effects, like in the the [Eff language][Eff] by Andrej Bauer and Matija Pretnar. Effects can be used instead of monad transformers, they are designed to be easier to use and to define.

Installation

------------

    cabal install effects

Using effects

-------------

Here's an example how to use the state effect from `Control.Effects.State`.

    example :: (Int, Int)

    example = run $ do

      with (ref 5) $ \x -> do

        with (ref 10) $ \y -> do

          x =: (+) <$> get x <*> get y

          y =: (+) <$> get x <*> get y

          (,) <$> get x <*> get y

Every instance of an effect is given a name (`x` and `y` in this example), which makes is possible to easily mix several instances of the same effect.

For more examples see [examples.hs](https://github.com/sjoerdvisscher/effects/blob/master/examples.hs). 

Another good example is the implementation of a [parser](https://github.com/nybble41/effects-parser) by Jesse McDonald.

[Eff]: http://math.andrej.com/category/programming/eff/?category_name=programming/eff