Safe Haskell | Safe-Inferred |
---|---|
Language | Haskell2010 |
Extend a monad with an accumulative write-only environment
Type
newtype WriterT w m a Source #
A transformer with monoidal write-only w, inner monad m, return a
WriterT (m (a, w)) |
Instances
Monoid w => MonadTrans (WriterT w) Source # | |
(Monad m, Alternative m, Monoid w) => Alternative (WriterT w m) Source # | |
(Monad m, Monoid w) => Applicative (WriterT w m) Source # | |
Defined in Mini.Transformers.WriterT | |
(Monad m, Monoid w) => Functor (WriterT w m) Source # | |
(Monad m, Monoid w) => Monad (WriterT w m) Source # | |
Runner
runWriterT :: WriterT w m a -> m (a, w) Source #
Unwrap a WriterT
computation