Safe Haskell	Safe-Inferred
Language	Haskell2010

Mini.Transformers.WriterT

Contents

Description

Extend a monad with an accumulative write-only environment

Synopsis

Type

newtype WriterT w m a Source #

A transformer with monoidal write-only w, inner monad m, return a

Constructors

WriterT (m (a, w))

Instances details

Monoid w => MonadTrans (WriterT w) Source #
Instance details Defined in Mini.Transformers.WriterT Methods lift :: Monad m => m a -> WriterT w m a Source #
(Monad m, Alternative m, Monoid w) => Alternative (WriterT w m) Source #
Instance details Defined in Mini.Transformers.WriterT Methods empty :: WriterT w m a # (<\|>) :: WriterT w m a -> WriterT w m a -> WriterT w m a # some :: WriterT w m a -> WriterT w m [a] # many :: WriterT w m a -> WriterT w m [a] #
(Monad m, Monoid w) => Applicative (WriterT w m) Source #
Instance details Defined in Mini.Transformers.WriterT Methods pure :: a -> WriterT w m a # (<>) :: WriterT w m (a -> b) -> WriterT w m a -> WriterT w m b # liftA2 :: (a -> b -> c) -> WriterT w m a -> WriterT w m b -> WriterT w m c # (>) :: WriterT w m a -> WriterT w m b -> WriterT w m b # (<*) :: WriterT w m a -> WriterT w m b -> WriterT w m a #
(Monad m, Monoid w) => Functor (WriterT w m) Source #
Instance details Defined in Mini.Transformers.WriterT Methods fmap :: (a -> b) -> WriterT w m a -> WriterT w m b # (<$) :: a -> WriterT w m b -> WriterT w m a #
(Monad m, Monoid w) => Monad (WriterT w m) Source #
Instance details Defined in Mini.Transformers.WriterT Methods (>>=) :: WriterT w m a -> (a -> WriterT w m b) -> WriterT w m b # (>>) :: WriterT w m a -> WriterT w m b -> WriterT w m b # return :: a -> WriterT w m a #

Runner

Unwrap a WriterT computation

tell :: Monad m => w -> WriterT w m () Source #

Append a value to the write-only environment