writer
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.
Construct a writer computation from a (result, output) pair.
Construct a writer computation from a (result, output) pair. (The inverse of runWriter.)
A writer monad parameterized by:
* w - the output to accumulate.
* m - The inner monad.
The return function produces the output mempty, while >>= combines the outputs of the subcomputations using mappend.
Extract the output from a writer computation.
* m = snd (runWriter
>
Map both the return value and output of a computation using the given function.
* (mapWriter f m) = f (runWriter
>
Map both the return value and output of a computation using the given function.
* (mapWriterT f m) = f
> (runWriterT
Unwrap a writer computation as a (result, output) pair. (The inverse of writer.)
A way to write XML and HTML with more efficient syntax.
Version 0.0.0.1