Safe Haskell	None
Language	Haskell2010

Cleff.Internal.Monad

Contents

Core types
Performing effect operations

Description

This module contains the definition of the Eff monad, which is basically an Env es -> IO a, as well as functions for manipulating the effect environment type Env. Most of the times, you won't need to use this module directly; user-facing functionalities are all exported via the Cleff module.

This is an internal module and its API may change even between minor versions. Therefore you should be extra careful if you're to depend on this module.

Synopsis

newtype InternalHandler e = InternalHandler {
- runHandler :: forall es. e (Eff es) ~> Eff es
}
type Env = Mem InternalHandler
newtype Eff es a = Eff {
- unEff :: Env es -> IO a
}
class KnownList (es :: [k])
class KnownList es => Subset (es :: [k]) (es' :: [k])
send :: e :> es => e (Eff es) ~> Eff es

Core types

newtype InternalHandler e Source #

The internal representation of effect handlers. This is just a natural transformation from the effect type e (Eff es) to the effect monad Eff es for any effect stack es.

In interpreting functions (see Cleff.Internal.Interpret), the user-facing Handler type is transformed into this type.

Constructors

InternalHandler
Fields runHandler :: forall es. e (Eff es) ~> Eff es

Instances

Instances details

Typeable e => Show (InternalHandler e) Source #	`show` (handler :: `InternalHandler` E) == "Handler E"
Instance details Defined in Cleff.Internal.Monad Methods showsPrec :: Int -> InternalHandler e -> ShowS # show :: InternalHandler e -> String # showList :: [InternalHandler e] -> ShowS #

type Env = Mem InternalHandler Source #

The effect memironment that stores handlers of any effect present in the stack es.

newtype Eff es a Source #

The extensible effect monad. A monad Eff es is capable of performing any effect in the effect stack es, which is a type-level list that holds all effects available. However, most of the times, for flexibility, es should be a polymorphic type variable, and you should use the (:>) and (:>>) operators in constraints to indicate what effects are in the stack. For example,

Reader String :> es, State Bool :> es => Eff es Integer

allows you to perform operations of the Reader String effect and the State Bool effect in a computation returning an Integer.

Constructors

Eff
Fields unEff :: Env es -> IO a

Instances

Instances details

IOE :> es => MonadBase IO (Eff es) Source #	Compatibility instance; use `MonadIO` if possible.
Instance details Defined in Cleff.Internal.Base Methods liftBase :: IO α -> Eff es α #
IOE :> es => MonadBaseControl IO (Eff es) Source #	Compatibility instance; use `MonadUnliftIO` if possible.
Instance details Defined in Cleff.Internal.Base Associated Types type StM (Eff es) a # Methods liftBaseWith :: (RunInBase (Eff es) IO -> IO a) -> Eff es a # restoreM :: StM (Eff es) a -> Eff es a #
Monad (Eff es) Source #
Instance details Defined in Cleff.Internal.Monad Methods (>>=) :: Eff es a -> (a -> Eff es b) -> Eff es b # (>>) :: Eff es a -> Eff es b -> Eff es b # return :: a -> Eff es a #
Functor (Eff es) Source #
Instance details Defined in Cleff.Internal.Monad Methods fmap :: (a -> b) -> Eff es a -> Eff es b # (<$) :: a -> Eff es b -> Eff es a #
MonadFix (Eff es) Source #
Instance details Defined in Cleff.Internal.Monad Methods mfix :: (a -> Eff es a) -> Eff es a #
Fail :> es => MonadFail (Eff es) Source #
Instance details Defined in Cleff.Fail Methods fail :: String -> Eff es a #
Applicative (Eff es) Source #
Instance details Defined in Cleff.Internal.Monad Methods pure :: a -> Eff es a # (<>) :: Eff es (a -> b) -> Eff es a -> Eff es b # liftA2 :: (a -> b -> c) -> Eff es a -> Eff es b -> Eff es c # (>) :: Eff es a -> Eff es b -> Eff es b # (<*) :: Eff es a -> Eff es b -> Eff es a #
IOE :> es => MonadIO (Eff es) Source #
Instance details Defined in Cleff.Internal.Base Methods liftIO :: IO a -> Eff es a #
IOE :> es => MonadThrow (Eff es) Source #
Instance details Defined in Cleff.Internal.Base Methods throwM :: Exception e => e -> Eff es a #
IOE :> es => MonadCatch (Eff es) Source #
Instance details Defined in Cleff.Internal.Base Methods catch :: Exception e => Eff es a -> (e -> Eff es a) -> Eff es a #
IOE :> es => MonadMask (Eff es) Source #
Instance details Defined in Cleff.Internal.Base Methods mask :: ((forall a. Eff es a -> Eff es a) -> Eff es b) -> Eff es b # uninterruptibleMask :: ((forall a. Eff es a -> Eff es a) -> Eff es b) -> Eff es b # generalBracket :: Eff es a -> (a -> ExitCase b -> Eff es c) -> (a -> Eff es b) -> Eff es (b, c) #
IOE :> es => PrimMonad (Eff es) Source #
Instance details Defined in Cleff.Internal.Base Associated Types type PrimState (Eff es) # Methods primitive :: (State# (PrimState (Eff es)) -> (# State# (PrimState (Eff es)), a #)) -> Eff es a #
IOE :> es => MonadUnliftIO (Eff es) Source #
Instance details Defined in Cleff.Internal.Base Methods withRunInIO :: ((forall a. Eff es a -> IO a) -> IO b) -> Eff es b #
Semigroup a => Semigroup (Eff es a) Source #
Instance details Defined in Cleff.Internal.Monad Methods (<>) :: Eff es a -> Eff es a -> Eff es a # sconcat :: NonEmpty (Eff es a) -> Eff es a # stimes :: Integral b => b -> Eff es a -> Eff es a #
Monoid a => Monoid (Eff es a) Source #
Instance details Defined in Cleff.Internal.Monad Methods mempty :: Eff es a # mappend :: Eff es a -> Eff es a -> Eff es a # mconcat :: [Eff es a] -> Eff es a #
type PrimState (Eff es) Source #
Instance details Defined in Cleff.Internal.Base type PrimState (Eff es) = RealWorld
type StM (Eff es) a Source #
Instance details Defined in Cleff.Internal.Base type StM (Eff es) a = a

Performing effect operations

class KnownList (es :: [k]) Source #

The list es list is concrete, i.e. is of the form '[a1, a2, ..., an], i.e. is not a type variable.

Instances

Instances details

KnownList ('[] :: [k]) Source #
Instance details Defined in Data.Rec Methods reifyLen :: Int
KnownList es => KnownList (e ': es :: [k]) Source #
Instance details Defined in Data.Rec Methods reifyLen :: Int

class KnownList es => Subset (es :: [k]) (es' :: [k]) Source #

es is a subset of es'.

Instances

Instances details

Subset ('[] :: [k]) (es :: [k]) Source #
Instance details Defined in Data.Rec Methods reifyIndices :: [Int]
(Subset es es', Elem e es') => Subset (e ': es :: [k]) (es' :: [k]) Source #
Instance details Defined in Data.Rec Methods reifyIndices :: [Int]

send :: e :> es => e (Eff es) ~> Eff es Source #

Perform an effect operation, i.e. a value of an effect type e :: Effect. This requires e to be in the effect stack.