writer package:transformers
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.)
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
<>):
Convert a writer computation into an accumulation computation.
Construct a writer computation from a (result, output) computation.
(The inverse of
runWriterT.)
A writer monad parameterized by:
- w - the output to accumulate.
- m - The inner monad.
The
return function produces the output
mempty, while
m >>= k combines the outputs of the
subcomputations using
mappend (also known as
<>):
A writer monad parameterized by:
- w - the output to accumulate.
- m - The inner monad.
The
return function produces the output
mempty, while
m >>= k combines the outputs of the
subcomputations using
mappend (also known as
<>):
Extract the output from a writer computation.
Extract the output from a writer computation.
Map both the return value and output of a computation using the given
function.
Map both the return value and output of a computation using the given
function.
Unwrap a writer computation as a (result, output) pair. (The inverse
of
writer.)
Unwrap a writer computation. (The inverse of
writerT.)
Extract the output from a writer computation.
Extract the output from a writer computation.
Map both the return value and output of a computation using the given
function.
Map both the return value and output of a computation using the given
function.
Unwrap a writer computation as a (result, output) pair. (The inverse
of
writer.)