27 Jan
2015
27 Jan
'15
5:14 p.m.
runSubStateT :: Monad m => (s -> s') -> (s' -> s) -> StateT s' m a -> StateT s m a runSubStateT to from m = StateT (\s -> liftM (\(a,s') -> (a,from s')) (runStateT m (to s))) Anyone ever needed something like this? Does it already exist in some form in the standard libraries? Ciao