Modulefused-effects-1.1.2.7Haskell2010

Control.Carrier.Writer.Church

A high-performance, strict, church-encoded carrier for Writer.

This carrier issues left-associated mappends, meaning that Monoids such as [] with poor performance for left-associated mappends are ill-suited for use with this carrier. Alternatives such as Endo, Seq, or DList may be preferred.

1 type
2 values

Packagefused-effects-1.1.2.7
Exports3
LanguageHaskell2010
LicenceBSD-3-Clause
SourceChurch.hs

Writer carrier

3 declarations

valuerunWriter :: Monoid w => (w -> a -> m b) -> WriterC w m a -> m b

Run a Writer effect with a Monoidal log, applying a continuation to the final log and result.

runWriter k (pure a) = k mempty a

runWriter k (tell w) = k w ()

runWriter k (listen (tell w)) = k w (w, ())

runWriter k (censor f (tell w)) = k (f w) ()

valueexecWriter :: (Monoid w, Applicative m) => WriterC w m a -> m w

Run a Writer effect with a Monoidal log, producing the final log and discarding the result value.

execWriter = runWriter (const . pure)

newtypenewtype WriterC w (m :: Type -> Type) a

Constructors

WriterC
- runWriterC :: StateC w m a

Instances10MonadTrans, Monad, Functor, MonadFix, MonadFail, Applicative, …

MonadTrans (WriterC w)Defined in fused-effects-1.1.2.7 · Control.Carrier.Writer.Church
Monad (WriterC w m)Defined in fused-effects-1.1.2.7 · Control.Carrier.Writer.Church
Functor (WriterC w m)Defined in fused-effects-1.1.2.7 · Control.Carrier.Writer.Church
MonadFix m => MonadFix (WriterC w m)Defined in fused-effects-1.1.2.7 · Control.Carrier.Writer.Church
MonadFail m => MonadFail (WriterC w m)Defined in fused-effects-1.1.2.7 · Control.Carrier.Writer.Church
Applicative (WriterC w m)Defined in fused-effects-1.1.2.7 · Control.Carrier.Writer.Church
Alternative m => Alternative (WriterC w m)Defined in fused-effects-1.1.2.7 · Control.Carrier.Writer.Church
(Alternative m, Monad m) => MonadPlus (WriterC w m)Defined in fused-effects-1.1.2.7 · Control.Carrier.Writer.Church
MonadIO m => MonadIO (WriterC w m)Defined in fused-effects-1.1.2.7 · Control.Carrier.Writer.Church
(Algebra sig m, Monoid w) => Algebra (Writer w :+: sig) (WriterC w m)Defined in fused-effects-1.1.2.7 · Control.Carrier.Writer.Church

Writer effect

0 declarations

module Control.Effect.Writer