writer -package:core-program
writer (a,w) embeds a simple writer action.
Construct a writer computation from a (result, output) pair.
Construct a writer computation from a (result, output) pair.
Construct a writer computation from a (result, output) pair. (The
inverse of
runWriter.)
Construct a writer computation from a (result, output) pair. (The
inverse of
runWriter.)
Like
write but uses the experimental
Refold API.
Internal
Construct a writer computation from a (result, output) pair.
Construct a writer computation from a (result, output) pair. (The
inverse of
runWriter.)
writer @tag (a, w) lifts a pure writer action (a, w)
to a monadic action in an arbitrary monad m with capability
HasWriter.
Appends w to the output of the writer capability tag
and returns the value a.
A writer monad parameterized by the type
w of output to
accumulate.
The
return function produces the output
mempty, while
>>= combines the outputs of the subcomputations using
mappend.
A writer monad parameterized by the type
w of output to
accumulate.
The
return function produces the output
mempty, while
>>= combines the outputs of the subcomputations using
mappend.
The WriterT monad transformer. This version builds its output lazily;
for a constant-space version with almost the same interface, see
Control.Monad.Trans.Writer.CPS.
A writer monad parameterized by the type
w of output to
accumulate.
The
return function produces the output
mempty, while
m >>= k combines the outputs of the
subcomputations using
mappend (also known as
<>):
An effect capable of emitting and intercepting messages.
Provides reexports of MonadWriter and related helpers.
Arrow transformer that adds accumulation of output.
Provide access to a write only value of type w.