Control.Monad.Trans.Reader.Extras

Documentation

runReaderM :: (Monad m, Monad (t m), MonadTrans t, MFunctor t) => ReaderT a (t Identity) c -> m a -> t m c

This function combines two different monadic effects, where one of the effects is a reader effect and the other is a producing effect.

This version results in the reader monad's inner effect to be wrapped around the producing effect. This requires the Reader inner effect to be an MFunctor on Identity.

This can enable past-Dependence. Elm has foldp : (a -> state -> state) -> state -> Signal a -> Signal state This is equivalent to a creating a StateT state (Signal m) ()

runReaderM is a more general form of StateT state (Signal m) () where given a reader monad to transform "a" to "c" with effects, and an "as" monad that produces "a"s with other effects, run the result of "as" through the reader monad to produce "c"s with both effects. runReaderM :: Monad m => Reader a (State s) c -> m a -> StateT s m c runReaderM :: Reader a (State s) c -> Signal STM a -> StateT state (Signal STM) c runReaderM :: Reader a (State s) c -> Pipes.Concurrent.Input a -> StateT state Pipes.Concurrent.Input c

runReaderM' :: (Monad m, Monad (t m), MonadTrans t, MFunctor t) => ReaderT a m c -> t Identity a -> t m c

An alternate form of runReaderM where the producing effect is wrapped around the reader monad's inner effect. This requires the producing effect to be an MFunctor on Identity.