Safe Haskell | Safe-Inferred |
---|---|
Language | Haskell2010 |
Extension of a monad with a write-only environment
Type
A monad with monoidal write-only type w, inner monad m, and return type a
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 # | |
Writing
Runners
runWriterT :: WriterT w m a -> m (a, w) Source #
Unwrap a WriterT