Re: [Haskell-cafe] An interesting monad: "Prompt"

Currently, yes; I was experimenting with type families. But it's pretty simple to get it to compile on 6.6.1: - remove the {-# LANGUAGE #-} pragma and replace with {-# OPTIONS_GHC -fglasgow-exts -fallow-undecidable-instances #-} - change the class declaration for MonadPrompter from

class Monad m => MonadPrompter m where type PromptType m :: * -> * prompt :: PromptType m a -> m a

to

class Monad m => MonadPrompter p m | m -> p where prompt :: p a -> m a

- change all the instance declarations from something like this:

instance MonadPrompter (XXX) where type PromptType (XXX) = YYY prompt = ...

to something like this:

instance MonadPrompter YYY (XXX) where prompt = ...

& you're done. -- ryan