simple-effects 0.8.0.2 → 0.9.0.0

raw patch · 10 files changed

+176/−190 lines, 10 files

Files

• simple-effects.cabal +1/−2
• src/Control/Effects.hs +36/−26
• src/Control/Effects/Early.hs +39/−9
• src/Control/Effects/List.hs +13/−11
• src/Control/Effects/Parallel.hs +2/−2
• src/Control/Effects/Reader.hs +17/−9
• src/Control/Effects/Signal.hs +30/−33
• src/Control/Effects/State.hs +36/−37
• src/Control/Effects1.hs +0/−59
• test/Main.hs +2/−2

@@ -1,5 +1,5 @@ name:                simple-effects
-version:             0.8.0.2
+version:             0.9.0.0
 synopsis:            A simple effect system that integrates with MTL
 description:         Please see README.md
 homepage:            https://gitlab.com/LukaHorvat/simple-effects
@@ -14,7 +14,6 @@ 
 library
   exposed-modules:     Control.Effects
-                     , Control.Effects1
                      , Control.Effects.State
                      , Control.Effects.Reader
                      , Control.Effects.List

@@ -1,56 +1,66 @@ {-# LANGUAGE TypeFamilies, MultiParamTypeClasses, FlexibleInstances, DeriveFunctor
            , GeneralizedNewtypeDeriving, UndecidableInstances, StandaloneDeriving
            , IncoherentInstances #-}
-module Control.Effects (module Control.Effects, module Control.Effects1) where
+{-# LANGUAGE DataKinds, PolyKinds, TypeInType, Rank2Types, TypeOperators, ConstraintKinds #-}
+module Control.Effects (module Control.Effects) where
 
-import Import 
+import Import
 import Control.Monad.Runnable
-import Control.Effects1
+import Data.Kind
 
-type family EffectMsg eff :: *
-type family EffectRes eff :: *
+data MsgOrRes = Msg | Res
+data family Effect (effKind :: Type) :: effKind -> MsgOrRes -> Type
 
-class Monad m => MonadEffect eff m where
-    -- | Use the effect described by 'eff'.
-    effect :: proxy eff -> EffectMsg eff -> m (EffectRes eff)
+class Monad m => MonadEffect effKind m where
+    -- | Use the effect described by 'method'.
+    effect :: Effect effKind method 'Msg -> m (Effect effKind method 'Res)
 
+newtype EffectWithKind effKind m = EffectWithKind
+    { getEffectWithKind :: forall method. Effect effKind method 'Msg -> m (Effect effKind method 'Res) }
+
 -- | The 'EffectHandler' is really just a 'ReaderT' carrying around the function that knows how to
 --   handle the effect.
-newtype EffectHandler eff m a = EffectHandler
-    { unpackEffectHandler :: ReaderT (EffectMsg eff -> m (EffectRes eff)) m a }
+newtype EffectHandler effKind m a = EffectHandler
+    { unpackEffectHandler :: ReaderT (EffectWithKind effKind m) m a }
     deriving ( Functor, Applicative, Monad, Alternative, MonadState s, MonadIO, MonadCatch
              , MonadThrow, MonadRandom )
 
-instance MonadTrans (EffectHandler eff) where
+instance MonadTrans (EffectHandler effKind) where
     lift = EffectHandler . lift
 
-instance RunnableTrans (EffectHandler eff) where
-    type TransformerState (EffectHandler eff) m = EffectMsg eff -> m (EffectRes eff)
-    type TransformerResult (EffectHandler eff) m a = a
+instance RunnableTrans (EffectHandler effKind) where
+    type TransformerState (EffectHandler effKind) m = EffectWithKind effKind m
+    type TransformerResult (EffectHandler effKind) m a = a
     currentTransState = EffectHandler ask
     restoreTransState = return
     runTransformer m = runReaderT (unpackEffectHandler m)
 
-instance MonadReader s m => MonadReader s (EffectHandler eff m) where
+instance MonadReader s m => MonadReader s (EffectHandler effKind m) where
     ask = EffectHandler (lift ask)
     local f (EffectHandler rdr) = EffectHandler (ReaderT $ local f . runReaderT rdr)
 
-deriving instance MonadBase b m => MonadBase b (EffectHandler eff m)
+deriving instance MonadBase b m => MonadBase b (EffectHandler effKind m)
 
-instance MonadBaseControl b m => MonadBaseControl b (EffectHandler eff m) where
-    type StM (EffectHandler eff m) a = StM (ReaderT (EffectMsg eff -> m (EffectRes eff)) m) a
+instance MonadBaseControl b m => MonadBaseControl b (EffectHandler effKind m) where
+    type StM (EffectHandler effKind m) a = StM (ReaderT (EffectWithKind effKind m) m) a
     liftBaseWith f = EffectHandler $ liftBaseWith $ \q -> f (q . unpackEffectHandler)
     restoreM = EffectHandler . restoreM
 
-instance {-# OVERLAPPABLE #-} (MonadEffect eff m, MonadTrans t, Monad (t m))
-         => MonadEffect eff (t m) where
+instance {-# OVERLAPPABLE #-} (MonadEffect method m, MonadTrans t, Monad (t m))
+         => MonadEffect method (t m) where
     {-# INLINE effect #-}
-    effect p msg = lift (effect p msg)
+    effect msg = lift (effect msg)
 
-instance Monad m => MonadEffect eff (EffectHandler eff m) where
+instance Monad m => MonadEffect effKind (EffectHandler effKind m) where
     {-# INLINE effect #-}
-    effect _ msg = EffectHandler (ReaderT ($ msg))
+    effect msg = EffectHandler (ReaderT (($ msg) . getEffectWithKind))
 
--- | Handle the effect described by 'eff'.
-handleEffect :: (EffectMsg eff -> m (EffectRes eff)) -> EffectHandler eff m a -> m a
-handleEffect f eh = runReaderT (unpackEffectHandler eh) f
+-- | Handle the effect described by 'effKind'.
+handleEffect ::
+    (forall method. Effect effKind method 'Msg -> m (Effect effKind method 'Res))
+    -> EffectHandler effKind m a -> m a
+handleEffect f eh = runReaderT (unpackEffectHandler eh) (EffectWithKind f)
+
+type family MonadEffects effs m :: Constraint where
+    MonadEffects '[] m = ()
+    MonadEffects (eff ': effs) m = (MonadEffect eff m, MonadEffects effs m)

@@ -1,5 +1,33 @@ {-# LANGUAGE RankNTypes, TypeFamilies, FlexibleContexts, ScopedTypeVariables, MultiParamTypeClasses #-}
-{-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE FlexibleInstances, DataKinds, GADTs #-}
+-- | A neat effect that you can use to get early returns in your functions. Here's how to use it.
+--
+--   Before:
+--
+-- @
+--   f = do
+--       m1 <- maybeFunc1
+--       case m1 of
+--           Nothing -> return "1 nothing"
+--           Just x -> do
+--               m2 <- maybeFunc2
+--               case m2 of
+--                   Nothing -> return "2 nothing"
+--                   Just y -> return (x <> y)
+-- @
+--
+--   After:
+--
+-- @
+--   f = handleEarly $ do
+--       m1 <- maybeFunc1
+--       x <- ifNothingEarlyReturn "1 nothing" m1
+--       m2 <- maybeFunc2
+--       y <- ifNothingEarlyReturn "2 nothing" m2
+--       return (x <> y)
+-- @
+--
+--   You can use the 'earlyReturn' function directily, or one of the helpers for common use cases.
 module Control.Effects.Early
     ( module Control.Effects, Early
     , earlyReturn, handleEarly, onlyDo, ifNothingEarlyReturn, ifNothingDo
@@ -9,21 +37,23 @@ 
 import Control.Effects
 
-newtype Early a = Early { getEarlyReturn :: a }
-type instance EffectMsg (Early a) = a
-type instance EffectRes (Early a) = Void
+newtype EarlyValue a = EarlyValue { getEarlyValue :: a }
+data Early a = Early
+data instance Effect (Early a) method mr where
+    EarlyMsg :: a -> Effect (Early a) 'Early 'Msg
+    EarlyRes :: { getEarlyRes :: Void } -> Effect (Early a) 'Early 'Res
 
-instance (Monad m, a ~ b) => MonadEffect (Early a) (ExceptT (Early b) m) where
-    effect _ = throwE . Early
+instance (Monad m, a ~ b) => MonadEffect (Early a) (ExceptT (EarlyValue b) m) where
+    effect (EarlyMsg a) = EarlyRes <$> throwE (EarlyValue a)
 
 -- | Allows you to return early from a function. Make sure you 'handleEarly' to get the actual
 --   result out.
 earlyReturn :: forall a b m. MonadEffect (Early a) m => a -> m b
-earlyReturn = fmap (getEarlyReturn . absurd) . effect (Proxy :: Proxy (Early a))
+earlyReturn a = fmap (getEarlyValue . absurd . getEarlyRes) . effect $ EarlyMsg a
 
 -- | Get the result from a computation. Either the early returned one, or the regular result.
-handleEarly :: Monad m => ExceptT (Early a) m a -> m a
-handleEarly = fmap (either getEarlyReturn id)
+handleEarly :: Monad m => ExceptT (EarlyValue a) m a -> m a
+handleEarly = fmap (either getEarlyValue id)
             . runExceptT
 
 -- | Only do the given action and exit early with it's result.

@@ -1,4 +1,6 @@ {-# LANGUAGE ScopedTypeVariables, TypeFamilies, FlexibleContexts, MultiParamTypeClasses #-}
+{-# LANGUAGE DataKinds, GADTs #-}
+-- | Add non-determinism to your monad. Uses the 'ListT' transformer under the hood.
 module Control.Effects.List
     ( module Control.Effects.List
     , module ListT ) where
@@ -9,22 +11,22 @@ import ListT hiding (take)
 
 import Control.Effects
-
-data NonDeterministic
+import Data.Kind
 
-type instance EffectMsg1 NonDeterministic = []
-type instance EffectRes1 NonDeterministic = Identity
-type instance EffectCon1 NonDeterministic a = ()
+newtype NonDeterministic = Choose Type
+data instance Effect NonDeterministic method mr where
+    ChooseMsg :: { getChooseMsg :: [a] } -> Effect NonDeterministic ('Choose a) 'Msg
+    ChooseRes :: { getChooseRes :: a } -> Effect NonDeterministic ('Choose a) 'Res
 
-instance Monad m => MonadEffect1 NonDeterministic (ListT m) where
-    effect1 _ = fmap Identity . fromFoldable
+instance Monad m => MonadEffect NonDeterministic (ListT m) where
+    effect (ChooseMsg list) = ChooseRes <$> fromFoldable list
 
 -- | Runs the rest of the computation for every value in the list
-choose :: MonadEffect1 NonDeterministic m => [a] -> m a
-choose = fmap runIdentity . effect1 (Proxy :: Proxy NonDeterministic)
+choose :: MonadEffect NonDeterministic m => [a] -> m a
+choose = fmap getChooseRes . effect . ChooseMsg
 
 -- | Signals that this branch of execution failed to produce a result.
-deadEnd :: MonadEffect1 NonDeterministic m => m a
+deadEnd :: MonadEffect NonDeterministic m => m a
 deadEnd = choose []
 
 -- | Execute all the effects and collect the result in a list.
@@ -42,7 +44,7 @@ foldAllResults :: Monad m => (r -> a -> m r) -> r -> ListT m a -> m r
 foldAllResults = fold
 
--- | Same as 'foldAllResults' but the folding function has the ability to terminate eary by
+-- | Same as 'foldAllResults' but the folding function has the ability to terminate early by
 --   returning Nothing.
 foldWithEarlyTermination :: Monad m => (r -> a -> m (Maybe r)) -> r -> ListT m a -> m r
 foldWithEarlyTermination = foldMaybe

@@ -1,7 +1,7 @@ {-# LANGUAGE ScopedTypeVariables, FlexibleContexts #-}
 module Control.Effects.Parallel where
 
-import Import
+import Import hiding (State)
 
 import GHC.MVar
 import GHC.IO.Unsafe
@@ -17,7 +17,7 @@     _ <- forkFinally proc (\_ -> putMVar h ())
     return h
 
-appendState :: forall s m a proxy. (Semigroup s, MonadEffectState s m)
+appendState :: forall s m a proxy. (Semigroup s, MonadEffect (State s) m)
             => proxy s -> m a -> m a
 appendState _ m = do
     s :: s <- getState

@@ -1,20 +1,28 @@ {-# LANGUAGE ScopedTypeVariables, TypeFamilies, FlexibleContexts #-}
+{-# LANGUAGE DataKinds, GADTs #-}
+-- | The regular old 'MonadReader' effect with some differences. First, there's no functional
+--   dependency limiting your stack to a single environment type. This means less type inference so
+--   it might not be enough to just write 'readEnv'. Write 'readEnv @MyEnvType' instead using
+--   TypeApplications.
+--
+--   Second, the function has a less generic name and is called 'readEnv'.
+--
+--   Third, since it's a part of this effect framework, you get a 'handleReadEnv' function with
+--   which you can provide a different environment implementation _at runtime_.
 module Control.Effects.Reader (module Control.Effects.Reader, module Control.Effects) where
 
-import Import
-
 import Control.Effects
 
-data ReadEnv e
-
-type instance EffectMsg (ReadEnv e) = ()
-type instance EffectRes (ReadEnv e) = e
+data ReadEnv e = ReadEnv
+data instance Effect (ReadEnv e) method mr where
+    ReadEnvMsg :: Effect (ReadEnv e) 'ReadEnv 'Msg
+    ReadEnvRes :: { getReadEnvRes :: e } -> Effect (ReadEnv e) 'ReadEnv 'Res
 
 readEnv :: forall e m. MonadEffect (ReadEnv e) m => m e
-readEnv = effect (Proxy :: Proxy (ReadEnv e)) ()
+readEnv = getReadEnvRes <$> effect ReadEnvMsg
 
-handleReadEnv :: m e -> EffectHandler (ReadEnv e) m a -> m a
-handleReadEnv = handleEffect . const
+handleReadEnv :: Functor m => m e -> EffectHandler (ReadEnv e) m a -> m a
+handleReadEnv m = handleEffect (\ReadEnvMsg -> ReadEnvRes <$> m)
 
 handleSubreader :: MonadEffect (ReadEnv e) m => (e -> e') -> EffectHandler (ReadEnv e') m a -> m a
 handleSubreader f = handleReadEnv (f <$> readEnv)

@@ -1,12 +1,17 @@ {-# LANGUAGE TypeFamilies, ScopedTypeVariables, FlexibleContexts, Rank2Types, ConstraintKinds #-}
-{-# LANGUAGE DeriveAnyClass, OverloadedStrings, MultiParamTypeClasses, NoMonomorphismRestriction #-}
+{-# LANGUAGE MultiParamTypeClasses, NoMonomorphismRestriction #-}
 {-# LANGUAGE FlexibleInstances, UndecidableInstances, DataKinds, TypeOperators #-}
+{-# LANGUAGE GADTs, TypeApplications #-}
 {-# OPTIONS_GHC -Wno-redundant-constraints #-}
+-- | This effect allows you to "throw" a signal. For the most part signals are the same as checked
+--   exceptions. The difference here is that the handler has the option to provide the value that
+--   will be the result /of calling the 'signal' function/. This effectively allows you to have
+--   recoverable exceptions at the throw site, instead of just at the handling site.
 module Control.Effects.Signal
-    ( MonadEffectSignal(..), ResumeOrBreak(..), throwSignal, handleSignal
+    ( ResumeOrBreak(..), Signal, throwSignal, handleSignal
     , Throws, handleException, handleToEither, module Control.Effects
     , module Control.Monad.Trans.Except, MaybeT(..), discardAllExceptions, showAllExceptions
-    , Handles(..), handleToEitherRecursive, SomeSignal ) where
+    , Handles(..), handleToEitherRecursive, SomeSignal, signal ) where
 
 import Import
 import Control.Monad.Trans.Except
@@ -15,11 +20,12 @@ import Control.Effects
 import Control.Monad.Runnable
 
-data Signal a b
-type instance EffectMsg (Signal a b) = a
-type instance EffectRes (Signal a b) = b
+data Signal a b = Signal
+data instance Effect (Signal a b) method mr where
+    SignalMsg :: a -> Effect (Signal a b) 'Signal 'Msg
+    SignalRes :: { getSignalRes :: b } -> Effect (Signal a b) 'Signal 'Res
 
-data SomeSignal = SomeSignal { getSomeSignal :: Text } deriving (Eq, Ord, Read, Show)
+newtype SomeSignal = SomeSignal { getSomeSignal :: Text } deriving (Eq, Ord, Read, Show)
 
 type family UnhandledError a b :: ErrorMessage where
     UnhandledError a Void =
@@ -31,35 +37,21 @@      ':$$: 'TL.Text "You need to handle all the signals before running the computation"
 
 instance {-# OVERLAPPABLE #-} Monad m => MonadEffect (Signal e b) (ExceptT e m) where
-    effect _ = throwE
+    effect (SignalMsg a) = throwE a
 instance (Show e, Monad m) => MonadEffect (Signal e b) (ExceptT SomeSignal m) where
-    effect _ = throwE . SomeSignal . pack . show
+    effect (SignalMsg a) = throwE . SomeSignal . pack . show $ a
 instance Monad m => MonadEffect (Signal a b) (MaybeT m) where
-    effect _ _ = mzero
+    effect _ = mzero
 instance TypeError (UnhandledError a b)
       => MonadEffect (Signal a b) IO where
     effect = undefined
--- | This class allows you to "throw" a signal. For the most part signals are the same as checked
---   exceptions. The difference here is that the handler has the option to provide the value that
---   will be the result /of calling the 'signal' function/. This effectively allows you to have
---   recoverable exceptions at the call site, instead of just at the handling site.
---
---   This class can be considered an alias for @'MonadEffect' ('Signal' a b)@ so your code isn't
---   required to provide any instances.
-class MonadEffect (Signal a b) m => MonadEffectSignal a b m where
-    -- | There are no restrictions on the type of values that can be thrown or returned.
-    signal :: a -> m b
-    signal = effect (Proxy :: Proxy (Signal a b))
+instance (Monad m, b ~ c) => MonadEffect (Signal a c) (EffectHandler (Signal a b) m) where
+    effect = effect @(Signal a b)
 
-type Throws e m = MonadEffectSignal e Void m
+signal :: MonadEffect (Signal a b) m => a -> m b
+signal a = getSignalRes <$> effect (SignalMsg a)
 
-instance (Monad m, b ~ c) => MonadEffectSignal a c (EffectHandler (Signal a b) m)
-instance Monad m => MonadEffectSignal a b (MaybeT m)
-instance {-# OVERLAPPABLE #-} Monad m => MonadEffectSignal e b (ExceptT e m)
-instance (Monad m, Show e) => MonadEffectSignal e b (ExceptT SomeSignal m)
-instance MonadEffect (Signal a b) IO => MonadEffectSignal a b IO
-instance {-# OVERLAPPABLE #-} (MonadEffectSignal a b m, MonadTrans t, Monad (t m))
-         => MonadEffectSignal a b (t m)
+type Throws e m = MonadEffect (Signal e Void) m
 
 -- | The handle function will return a value of this type.
 data ResumeOrBreak b c = Resume b -- ^ Give a value to the caller of 'signal' and keep going.
@@ -85,13 +77,18 @@ -- | Handle signals of a computation. The handler function has the option to provide a value
 --   to the caller of 'signal' and continue execution there, or do what regular exception handlers
 --   do and continue execution after the handler.
-handleSignal :: Monad m
+handleSignal :: forall a b c m. Monad m
              => (a -> m (ResumeOrBreak b c))
              -> EffectHandler (Signal a b) (ExceptT c m) c
              -> m c
 handleSignal f = fmap collapseEither
                . runExceptT
-               . handleEffect (resumeOrBreak return throwE <=< lift . f)
+               . handleEffect h
+    where
+    h :: forall method. Effect (Signal a b) method 'Msg -> ExceptT c m (Effect (Signal a b) method 'Res)
+    h (SignalMsg a) = do
+        rb <- lift (f a)
+        resumeOrBreak (return . SignalRes) throwE rb
 
 -- | This handler can only behave like a regular exception handler. If used along with 'throwSignal'
 --   this module behaves like regular checked exceptions.
@@ -102,7 +99,7 @@ handleToEither :: ExceptT e m a -> m (Either e a)
 handleToEither = runExceptT
 
--- | Discard all the 'Throws' and 'MonadEffectSignal' constraints. If any exception was thrown
+-- | Discard all the 'Throws' and 'Signal' constraints. If any exception was thrown
 --   the result will be 'Nothing'.
 discardAllExceptions :: MaybeT m a -> m (Maybe a)
 discardAllExceptions = runMaybeT
@@ -111,7 +108,7 @@ mapLeft f (Left a) = Left (f a)
 mapLeft _ (Right b) = Right b
 
--- | Satisfies all the 'Throws' and 'MonadEffectSignal' constraints /if/ they all throw 'Show'able
+-- | Satisfies all the 'Throws' and 'Signal' constraints /if/ they all throw 'Show'able
 --   exceptions. The first thrown exception will be shown and returned as a 'Left' result.
 showAllExceptions :: Functor m => ExceptT SomeSignal m a -> m (Either Text a)
 showAllExceptions = fmap (mapLeft getSomeSignal) . runExceptT

@@ -1,67 +1,66 @@ {-# LANGUAGE TypeFamilies, ScopedTypeVariables, FlexibleContexts, Rank2Types, ConstraintKinds #-}
 {-# LANGUAGE MultiParamTypeClasses, GADTs #-}
-module Control.Effects.State (module Control.Effects.State, module Control.Effects1) where
+{-# LANGUAGE DataKinds, TypeInType #-}
+-- | The 'MonadState' you know and love with some differences. First, there's no functional
+--   dependency limiting your stack to a single state type. This means less type inference so
+--   it might not be enough to just write 'getState'. Write 'getState @MyStateType' instead using
+--   TypeApplications.
+--
+--   Second, the functions have less generic names and are called 'getState' and 'setState'.
+--
+--   Third, since it's a part of this effect framework, you get a 'handleState' function with
+--   which you can provide a different state implementation _at runtime_.
+module Control.Effects.State (module Control.Effects.State, module Control.Effects) where
 
 import Import hiding (State)
 import Data.IORef
 
-import Control.Effects1
-
-data State s
-data Get
-data Set
-data StateMessage s a where
-    GetMessage :: StateMessage s Get
-    SetMessage :: !s -> StateMessage s Set
-data StateResult s a where
-    GetResult :: { getGetResult :: !s } -> StateResult s Get
-    SetResult :: StateResult s Set
-
-type instance EffectMsg1 (State s) = StateMessage s
-type instance EffectRes1 (State s) = StateResult s
-type instance EffectCon1 (State s) a = ()
-
-instance Monad m => MonadEffect1 (State s) (StateT s m) where
-    effect1 _ GetMessage = GetResult <$> get
-    effect1 _ (SetMessage s) = SetResult <$ put s
-    {-# INLINE effect1 #-}
+import Control.Effects
 
-type MonadEffectState s m = MonadEffect1 (State s) m
+data State s = Get | Set
+data instance Effect (State s) method mr where
+    GetStateMsg :: Effect (State s) 'Get 'Msg
+    GetStateRes :: { getGetStateRes :: s } -> Effect (State s) 'Get 'Res
+    SetStateMsg :: s -> Effect (State s) 'Set 'Msg
+    SetStateRes :: Effect (State s) 'Set 'Res
 
-stateEffect :: forall s a m. MonadEffectState s m
-            => StateMessage s a -> m (StateResult s a)
-stateEffect = effect1 (Proxy :: Proxy (State s))
-{-# INLINE stateEffect #-}
+instance Monad m => MonadEffect (State s) (StateT s m) where
+    effect GetStateMsg = GetStateRes <$> get
+    effect (SetStateMsg s) = SetStateRes <$ put s
+    {-# INLINE effect #-}
 
-getState :: forall s m. MonadEffectState s m => m s
-getState = getGetResult <$> stateEffect GetMessage
+getState :: forall s m. MonadEffect (State s) m => m s
+getState = getGetStateRes <$> effect GetStateMsg
 {-# INLINE getState #-}
 
-setState :: forall s m. MonadEffectState s m => s -> m ()
-setState s = void $ stateEffect (SetMessage s)
+setState :: forall s m. MonadEffect (State s) m => s -> m ()
+setState s = void $ effect (SetStateMsg s)
 {-# INLINE setState #-}
 
-modifyState :: forall s m. MonadEffectState s m => (s -> s) -> m ()
+modifyState :: forall s m. MonadEffect (State s) m => (s -> s) -> m ()
 modifyState f = do
     s <- getState
     let s' = f s in s' `seq` setState s'
 {-# INLINE modifyState #-}
 
+-- | Handle the 'MonadEffect (State s)' constraint by providing custom handling functions.
 handleState :: forall m s a. Monad m => m s -> (s -> m ())
-            -> EffectHandler1 (State s) m a -> m a
+            -> EffectHandler (State s) m a -> m a
 handleState getter setter =
-    handleEffect1 handler
-    where handler :: forall b. StateMessage s b -> m (StateResult s b)
-          handler GetMessage = GetResult <$> getter
-          handler (SetMessage s) = SetResult <$ setter s
+    handleEffect handler
+    where handler :: forall method. Effect (State s) method 'Msg -> m (Effect (State s) method 'Res)
+          handler GetStateMsg = GetStateRes <$> getter
+          handler (SetStateMsg s) = SetStateRes <$ setter s
 {-# INLINE handleState #-}
 
-handleStateIO :: MonadIO m => s -> EffectHandler1 (State s) m a -> m a
+-- | Handle the state requirement using an 'IORef'.
+handleStateIO :: MonadIO m => s -> EffectHandler (State s) m a -> m a
 handleStateIO initial m = do
     ref <- liftIO (newIORef initial)
     m & handleState (liftIO (readIORef  ref)) (liftIO . writeIORef ref)
 {-# INLINE handleStateIO #-}
 
+-- | Handle the state requirement using the standard 'StateT' transformer.
 handleStateT :: Monad m => s -> StateT s m a -> m a
 handleStateT = flip evalStateT
 {-# INLINE handleStateT #-}

@@ -1,59 +0,0 @@-{-# LANGUAGE TypeFamilies, MultiParamTypeClasses, FlexibleInstances, DeriveFunctor
-           , GeneralizedNewtypeDeriving, UndecidableInstances, StandaloneDeriving
-           , IncoherentInstances, RankNTypes, ConstraintKinds #-}
-module Control.Effects1 where
-
-import Import
-
-import Control.Monad.Runnable
-
-type family EffectMsg1 eff :: * -> *
-type family EffectRes1 eff :: * -> *
-type family EffectCon1 eff a :: Constraint
-
-class Monad m => MonadEffect1 eff m where
-    -- | Use the effect described by 'eff'.
-    effect1 :: EffectCon1 eff a => proxy eff -> EffectMsg1 eff a -> m (EffectRes1 eff a)
-
-newtype EffHandling1 eff m = EffHandling1 {
-    getHandling1 :: forall a. EffectCon1 eff a => EffectMsg1 eff a -> m (EffectRes1 eff a) }
-
--- | The 'EffectHandler1' is really just a 'ReaderT' carrying around the function that knows how to
---   handle the effect.
-newtype EffectHandler1 eff m a = EffectHandler1
-    { unpackEffectHandler1 :: ReaderT (EffHandling1 eff m) m a }
-    deriving ( Functor, Applicative, Monad, Alternative, MonadState s, MonadIO, MonadCatch
-             , MonadThrow, MonadRandom )
-
-instance MonadTrans (EffectHandler1 eff) where
-    lift = EffectHandler1 . lift
-
-instance RunnableTrans (EffectHandler1 eff) where
-    type TransformerState (EffectHandler1 eff) m = EffHandling1 eff m
-    type TransformerResult (EffectHandler1 eff) m a = a
-    currentTransState = EffectHandler1 ask
-    restoreTransState = return
-    runTransformer m = runReaderT (unpackEffectHandler1 m)
-
-instance MonadReader s m => MonadReader s (EffectHandler1 eff m) where
-    ask = EffectHandler1 (lift ask)
-    local f (EffectHandler1 rdr) = EffectHandler1 (ReaderT $ local f . runReaderT rdr)
-
-deriving instance MonadBase IO m => MonadBase IO (EffectHandler1 eff m)
-
-instance MonadBaseControl IO m => MonadBaseControl IO (EffectHandler1 eff m) where
-    type StM (EffectHandler1 eff m) a = StM (ReaderT (EffHandling1 eff m) m) a
-    liftBaseWith f = EffectHandler1 $ liftBaseWith $ \q -> f (q . unpackEffectHandler1)
-    restoreM = EffectHandler1 . restoreM
-
-instance {-# OVERLAPPABLE #-} (MonadEffect1 eff m, MonadTrans t, Monad (t m))
-         => MonadEffect1 eff (t m) where
-    effect1 p msg = lift (effect1 p msg)
-
-instance Monad m => MonadEffect1 eff (EffectHandler1 eff m) where
-    effect1 _ msg = EffectHandler1 (ReaderT (($ msg) . getHandling1))
-
--- | Handle the effect described by 'eff'.
-handleEffect1 :: (forall a. EffectCon1 eff a => EffectMsg1 eff a -> m (EffectRes1 eff a))
-              -> EffectHandler1 eff m b -> m b
-handleEffect1 f eh = runReaderT (unpackEffectHandler1 eh) (EffHandling1 f)

@@ -37,7 +37,7 @@ testEarly2 = handleEarly $
     earlyReturn 'a'
 
-orderTest :: (Handles Bool m, MonadEffectState Int m, MonadIO m) => m ()
+orderTest :: (Handles Bool m, MonadEffect (State Int) m, MonadIO m) => m ()
 orderTest = do
     setState (1 :: Int)
     _ :: Either Bool () <- handleToEitherRecursive $ do
@@ -50,7 +50,7 @@ inc :: Int -> Int
 inc !x = x + 1
 
-task :: (MonadEffectState Int m) => m Int
+task :: (MonadEffect (State Int) m) => m Int
 task = do
     replicateM_ 10000000 (modifyState inc)
     st <- getState