Safe Haskell	None
Language	Haskell2010

Control.Tracer.Transformers

Synopsis

newtype Counting a = Counting Int
newtype Folding a f = Folding f
counting :: forall m a. MonadIO m => Tracer m ( Counting a) -> m ( Tracer m a)
fanning :: forall m a. (a -> Tracer m a) -> Tracer m a
folding :: forall m f a. MonadIO m => (f -> a -> f) -> f -> Tracer m ( Folding a f) -> m ( Tracer m a)

Documentation

Constructors

Constructors

Folding f

counting :: forall m a. MonadIO m => Tracer m ( Counting a) -> m ( Tracer m a) Source #

A stateful tracer transformer that substitutes messages with a monotonically incrementing occurence count.

fanning :: forall m a. (a -> Tracer m a) -> Tracer m a Source #

A pure tracer combinator that allows to decide a further tracer to use, based on the message being processed.

folding :: forall m f a. MonadIO m => (f -> a -> f) -> f -> Tracer m ( Folding a f) -> m ( Tracer m a) Source #

A generalised trace transformer that provides evolving state, defined as a strict left fold.