MyState.hs

data MyState s a = MyState (s -> (a, s))

get :: MyState s s
get = undefined

put :: s -> MyState s ()
put = undefined

modify :: (s -> s) -> MyState s ()
modify = undefined

instance Functor (MyState s) where
    -- fmap :: (a -> b) -> (MyState s) a -> (MyState s) b
    fmap = undefined
    
instance Applicative (MyState s) where
    -- pure :: a -> (MyState s) a
    pure = undefined
    
    -- (<*>) :: (MyState s) (a -> b) -> (MyState s) a -> (MyState s) b
    (<*>) = undefined

instance Monad (MyState s) where
    -- return :: a -> (MyState s) a
    return = pure
    
    -- (>>=) :: (MyState s) a -> (a -> (MyState s) b) -> (MyState s) b
    (>>=) = undefined

MyStateT.hs

data MyStateT s m a = MyStateT (s -> m (a, s))
 
get :: Monad m => MyStateT s m s
get = undefined
 
put :: Monad m => s -> MyStateT s m ()
put = undefined
 
modify :: Monad m => (s -> s) -> MyStateT s m ()
modify = undefined
 
instance Monad m => Functor (MyStateT s m) where
    -- fmap :: (a -> b) -> (MyStateT s m) a -> (MyStateT s m) b
    fmap = undefined
    
instance Monad m => Applicative (MyStateT s m) where
    -- pure :: a -> (MyStateT s m) a
    pure = undefined
    
    -- (<*>) :: (MyStateT s m) (a -> b) -> (MyStateT s m) a -> (MyStateT s m) b
    (<*>) = undefined
 
instance Monad m => Monad (MyStateT s m) where
    -- return :: a -> (MyStateT s m) a
    return = pure
    
    -- (>>=) :: (MyStateT s m) a -> (a -> (MyStateT s m) b) -> (MyStateT s m) b
    (>>=) = undefined