src/Reflex/EventWriter/Class.hs · reflex

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1-- | This module defines the 'EventWriter' class.

2{-# LANGUAGE CPP #-}

3{-# LANGUAGE FlexibleInstances #-}

4{-# LANGUAGE FunctionalDependencies #-}

5{-# LANGUAGE UndecidableInstances #-}

6#ifdef USE_REFLEX_OPTIMIZER

7{-# OPTIONS_GHC -fplugin=Reflex.Optimizer #-}

8#endif

9module Reflex.EventWriter.Class

10 ( EventWriter (..)

11 ) where

13import Control.Monad.Reader (ReaderT, lift)

14import Data.Semigroup (Semigroup)

16import Reflex.Class (Event)

19-- | 'EventWriter' efficiently collects 'Event' values using 'tellEvent'

20-- and combines them via 'Semigroup' to provide an 'Event' result.

21class (Monad m, Semigroup w) => EventWriter t w m | m -> t w where

22 tellEvent :: Event t w -> m ()

25instance EventWriter t w m => EventWriter t w (ReaderT r m) where

26 tellEvent = lift . tellEvent