6c54120 · patch · git.iko.soy

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Adds withEventWriterT.

6c54120Dave Laing9 years ago

src/Reflex/EventWriter.hs+14

@@ -19,6 +19,7 @@ module Reflex.EventWriter

19 , EventWriter (..)

20 , runWithReplaceEventWriterTWith

21 , sequenceDMapWithAdjustEventWriterTWith

22+ , withEventWriterT

22 ) where

23 ) where

24import Reflex.Class

25import Reflex.Class

@@ -176,3 +177,16 @@ instance (MonadQuery t q m, Monad m) => MonadQuery t q (EventWriterT t w m) wher

176 tellQueryIncremental = lift . tellQueryIncremental

177 tellQueryIncremental = lift . tellQueryIncremental

177 askQueryResult = lift askQueryResult

178 askQueryResult = lift askQueryResult

178 queryIncremental = lift . queryIncremental

179 queryIncremental = lift . queryIncremental

180+

181+-- | Map a function over the output of a 'EventWriterT'.

182+withEventWriterT :: (Monoid w, Monoid w', Reflex t, MonadHold t m, MonadFix m)

183+ => (w -> w')

184+ -> EventWriterT t w m a

185+ -> EventWriterT t w' m a

186+withEventWriterT f ew = do

187+ (r, e) <- lift $ do

188+ (r, e) <- runEventWriterT ew

189+ let e' = fmap f e

190+ return (r, e')

191+ tellEvent e

192+ return r