src/Reflex/EventWriter/Class.hs · patch

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

2{-# LANGUAGE CPP #-}

3{-# LANGUAGE FlexibleInstances #-}

4{-# LANGUAGE FunctionalDependencies #-}

5{-# LANGUAGE MultiParamTypeClasses #-}

6{-# LANGUAGE UndecidableInstances #-}

7#ifdef USE_REFLEX_OPTIMIZER

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

9#endif

10module Reflex.EventWriter.Class

11 ( EventWriter (..)

12 ) where

14import Control.Monad.Reader (ReaderT, lift)

15import Data.Semigroup (Semigroup)

17import Reflex.Class (Event)

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

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

22class (Monad m, Semigroup w) => EventWriter t w m | m -> t w where

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

26instance EventWriter t w m => EventWriter t w (ReaderT r m) where

27 tellEvent = lift . tellEvent