Safe Haskell	Safe-Inferred
Language	Haskell2010

Mini.Transformers.StateT

Contents

Description

Extend a monad with a modifiable environment

Synopsis

Type

newtype StateT s m a Source #

A transformer with state s, inner monad m, return a

Constructors

StateT (s -> m (a, s))

Instances details

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

Runner

runStateT :: StateT s m a -> s -> m (a, s) Source #

Unwrap a StateT computation with an initial state

Fetch the current state

modify :: Monad m => (s -> s) -> StateT s m () Source #

Update the current state with an operation

put :: Monad m => s -> StateT s m () Source #

Overwrite the current state with a value