Safe Haskell | Safe-Inferred |
---|---|
Language | Haskell2010 |
Synopsis
- data Lift sig m k where
- sendM :: (Has (Lift n) sig m, Functor n) => n a -> m a
- sendIO :: Has (Lift IO) sig m => IO a -> m a
- liftWith :: Has (Lift n) sig m => (forall ctx. Functor ctx => Handler ctx m n -> ctx () -> n (ctx a)) -> m a
- class Monad m => Algebra sig m | m -> sig
- type Has eff sig m = (Members eff sig, Algebra sig m)
- run :: Identity a -> a
Lift effect
data Lift sig m k where Source #
Since: 1.0.0.0
sendM :: (Has (Lift n) sig m, Functor n) => n a -> m a Source #
Given a Lift n
constraint in a signature carried by m
, sendM
promotes arbitrary actions of type n a
to m a
. It is spiritually
similar to lift
from the MonadTrans
typeclass.
Since: 1.0.0.0
sendIO :: Has (Lift IO) sig m => IO a -> m a Source #
A type-restricted variant of sendM
for IO
actions.
This is particularly useful when you have a
constraint for the use of Has
(Lift
IO
) sig mliftWith
, and want to run an action abstracted over MonadIO
. IO
has a MonadIO
instance, and sendIO
’s type restricts the action’s type to IO
without further type annotations.
Since: 1.0.2.0
liftWith :: Has (Lift n) sig m => (forall ctx. Functor ctx => Handler ctx m n -> ctx () -> n (ctx a)) -> m a Source #
Run actions in an outer context.
This can be used to provide interoperation with base
functionality like Control.Exception.
:catch
liftWith
$ \ hdl ctx ->catch
(hdl (m <$ ctx)) (hdl . (<$ ctx) . h)
The higher-order function takes both an initial context, and a handler phrased as a distributive law (as described in the documentation for Handler
). This handler takes actions lifted into a context functor, which can be either the initial context, or the derived context produced by handling a previous action.
As with MonadBaseControl
, care must be taken when lifting functions like Control.Exception.
which don’t use the return value of one of their actions, as this can lead to dropped effects.finally
Since: 1.0.0.0
Re-exports
class Monad m => Algebra sig m | m -> sig Source #
The class of carriers (results) for algebras (effect handlers) over signatures (effects), whose actions are given by the alg
method.
Since: 1.0.0.0
Instances
Algebra Choose NonEmpty Source # | |
Algebra Empty Maybe Source # | |
Algebra NonDet List Source # | |
Algebra sig m => Algebra sig (Choosing m) Source # | |
Algebra sig m => Algebra sig (Ap m) Source # | This instance permits effectful actions to be lifted into the mappend <$> act1 <*> (mappend <$> act2 <*> act3) is equivalent to getAp (act1 <> act2 <> act3) Since: 1.0.1.0 |
Algebra sig m => Algebra sig (Alt m) Source # | This instance permits effectful actions to be lifted into the a <|> b <|> c <|> d is equivalent to getAlt (mconcat [a, b, c, d]) Since: 1.0.1.0 |
Algebra sig m => Algebra sig (IdentityT m) Source # | |
Algebra (Lift Identity) Identity Source # | |
Algebra (Lift IO) IO Source # | |
Algebra (Error e) (Either e) Source # | |
Monad m => Algebra (Lift m) (LiftC m) Source # | |
Monoid w => Algebra (Writer w) ((,) w) Source # | |
Algebra (Reader r) ((->) r) Source # | |
Algebra sig m => Algebra (Choose :+: sig) (ChooseC m) Source # | |
Algebra sig m => Algebra (Cull :+: (NonDet :+: sig)) (CullC m) Source # | |
Algebra sig m => Algebra (Cut :+: (NonDet :+: sig)) (CutC m) Source # | |
Algebra sig m => Algebra (Empty :+: sig) (EmptyC m) Source # | |
Algebra sig m => Algebra (Empty :+: sig) (EmptyC m) Source # | |
Algebra sig m => Algebra (Empty :+: sig) (MaybeT m) Source # | |
Algebra sig m => Algebra (Fail :+: sig) (FailC m) Source # | |
Algebra sig m => Algebra (Fresh :+: sig) (FreshC m) Source # | |
Algebra sig m => Algebra (Fresh :+: sig) (FreshC m) Source # | |
Algebra sig m => Algebra (NonDet :+: sig) (NonDetC m) Source # | |
Algebra sig m => Algebra (Trace :+: sig) (TraceC m) Source # | |
(MonadIO m, Algebra sig m) => Algebra (Trace :+: sig) (TraceC m) Source # | |
Algebra sig m => Algebra (Trace :+: sig) (TraceC m) Source # | |
(Algebra sig m, Monoid w) => Algebra (Accum w :+: sig) (AccumC w m) Source # | |
(Algebra sig m, Semigroup w, MonadIO m) => Algebra (Accum w :+: sig) (AccumC w m) Source # | |
(Algebra sig m, Monoid w) => Algebra (Accum w :+: sig) (AccumC w m) Source # | |
(Algebra sig m, Monoid w) => Algebra (Accum w :+: sig) (AccumT w m) Source # | |
Algebra sig m => Algebra (Error e :+: sig) (ErrorC e m) Source # | |
Algebra sig m => Algebra (Error e :+: sig) (ErrorC e m) Source # | |
Algebra sig m => Algebra (Error e :+: sig) (ExceptT e m) Source # | |
Algebra sig m => Algebra (Reader r :+: sig) (ReaderC r m) Source # | |
Algebra sig m => Algebra (Reader r :+: sig) (ReaderT r m) Source # | |
Algebra sig m => Algebra (State s :+: sig) (StateC s m) Source # | |
(MonadIO m, Algebra sig m) => Algebra (State s :+: sig) (StateC s m) Source # | |
Algebra sig m => Algebra (State s :+: sig) (StateC s m) Source # | |
Algebra sig m => Algebra (State s :+: sig) (StateC s m) Source # | |
Algebra sig m => Algebra (State s :+: sig) (StateT s m) Source # | |
Algebra sig m => Algebra (State s :+: sig) (StateT s m) Source # | |
Algebra sig m => Algebra (Throw e :+: sig) (ThrowC e m) Source # | |
(Algebra sig m, Monoid w) => Algebra (Writer w :+: sig) (WriterC w m) Source # | |
(Monoid w, Algebra sig m) => Algebra (Writer w :+: sig) (WriterC w m) Source # | |
(Algebra sig m, Monoid w) => Algebra (Writer w :+: sig) (WriterT w m) Source # | |
(Algebra sig m, Monoid w) => Algebra (Writer w :+: sig) (WriterT w m) Source # | |
(Algebra sig m, Monoid w) => Algebra (Writer w :+: sig) (WriterT w m) Source # | |
(Reifies s (Interpreter eff m), Algebra sig m) => Algebra (eff :+: sig) (InterpretC s eff m) Source # | |
Defined in Control.Carrier.Interpret alg :: forall ctx (n :: Type -> Type) a. Functor ctx => Handler ctx n (InterpretC s eff m) -> (eff :+: sig) n a -> ctx () -> InterpretC s eff m (ctx a) Source # | |
Algebra (eff :+: sig) (sub m) => Algebra (Labelled label eff :+: sig) (Labelled label sub m) Source # | |
(Algebra sig m, Monoid w) => Algebra (Reader r :+: (Writer w :+: (State s :+: sig))) (RWST r w s m) Source # | |
(Algebra sig m, Monoid w) => Algebra (Reader r :+: (Writer w :+: (State s :+: sig))) (RWST r w s m) Source # | |
(Algebra sig m, Monoid w) => Algebra (Reader r :+: (Writer w :+: (State s :+: sig))) (RWST r w s m) Source # | |
(LabelledMember label sub sig, Algebra sig m) => Algebra (sub :+: sig) (UnderLabel label sub m) Source # | |
Defined in Control.Effect.Labelled alg :: forall ctx (n :: Type -> Type) a. Functor ctx => Handler ctx n (UnderLabel label sub m) -> (sub :+: sig) n a -> ctx () -> UnderLabel label sub m (ctx a) Source # |
type Has eff sig m = (Members eff sig, Algebra sig m) Source #
m
is a carrier for sig
containing eff
.
Note that if eff
is a sum, it will be decomposed into multiple Member
constraints. While this technically allows one to combine multiple unrelated effects into a single Has
constraint, doing so has two significant drawbacks:
- Due to a problem with recursive type families, this can lead to significantly slower compiles.
- It defeats
ghc
’s warnings for redundant constraints, and thus can lead to a proliferation of redundant constraints as code is changed.
Since: 1.0.0.0