Re: [Haskell-cafe] one-way monads

On Mon, May 19, 2008 at 10:54 PM, Zsolt SZALAI wrote:

Now, i'm getting familiar with monads, but there is a little discredit about one-way monads.

If someone claims that monads are "one-way" they are probably referring to the fact that it is impossible (without cheating!) to write a function of signature Monad m => m a -> a. So I think there's no 'discredit' here. For any specific monad, m, it's usually possible to write a function m a -> a. But that's a distinct claim. -- Dan