[Haskell-cafe] using IO monad in Iteratee

[wren ng thornton]

On 4/1/11 3:59 PM, Dmitry Olshansky wrote:
> But enumFile use IO monad instead of MonadIO class.
> [...]
> Is it possible to change enumFile to using MonadIO class?

Unless its changed significantly since I looked at it last (which it may 
well have), it's not possible. The problem is that what we'd really need 
is lowerIO :: m a -> IO a for the m in question; liftIO goes the wrong 
way. Of course, getting a lowerIO with the right semantics will be 
tricky for most monads.

-- 
Live well,
~wren