"Apfelmus, Heinrich" <apfel...@quantentunnel.de> wrote: > Ertugrul Soeylemez wrote: > > > Let me tell you that usually 90% of my code is monadic and there is > > really nothing wrong with that. I use especially State monads and > > StateT transformers very often, because they are convenient and are > > just a clean combinator frontend to what you would do manually > > without them: passing state. > > The insistence on avoiding monads by experienced Haskellers, in > particular on avoiding the IO monad, is motivated by the quest for > elegance. > > The IO and other monads make it easy to fall back to imperative > programming patterns to "get the job done". [...]
Often, the monadic solution _is_ the elegant solution. Please don't confuse monads with impure operations. I use the monadic properties of lists, often together with monad transformers, to find elegant solutions. As long as you're not abusing monads to program imperatively, I think, they are an excellent and elegant structure. I said that 90% of my code is monadic, not that 90% of it is in IO. I do use state monads where there is no more elegant solution than passing state around. It's simply that: you have a structure, which you modify continuously in a complex fashion, such as a neural network or an automaton. Monads are the way to go here, unless you want to do research and find a better way to express this. Personally I prefer this: somethingWithRandomsM :: (Monad m, Random a) => m a -> Something a over these: somethingWithRandoms1 :: [a] -> Something a somethingWithRandoms2 :: RandomGen g => g -> Something a Also I use monads a lot for displaying progress: lengthyComputation :: Monad m => (Progress -> m ()) -> m Result > Consciously excluding monads and restricting the design space to pure > functions is the basic tool of thought for finding such elegant > abstractions. [...] You don't need to exclude monads to restrict the design space to pure functions. Everything except IO and ST (and some related monads) is pure. As said, often monads _are_ the elegant solutions. Just look at parser monads. Greets, Ertugrul. -- nightmare = unsafePerformIO (getWrongWife >>= sex) http://blog.ertes.de/ _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
