Re: [Haskell-cafe] (a -> [b]) vs. [a -> b]

Uh, apologies. I got confused between reading your post and playing for a while, and answered the wrong question. /g On 2/2/07, J. Garrett Morris wrote:

On 2/2/07, Chad Scherrer wrote:

...

So in reality, I'm trying to construct something like f :: (a -> STM b) -> STM (a -> b)

I just figured it was a general monadic kind of problem, more simply expressed using lists. But the (!!) solution doesn't make sense in this context.

Perhaps this will work for you:

f x = join . liftM f

This typechecks, and seems to work as expected, e.g.:

Prelude Control.Concurrent.STM Control.Monad> atomically (f readTVar (newTVar 'a')) 'a'

/g

-- It is myself I have never met, whose face is pasted on the underside of my mind.

-- It is myself I have never met, whose face is pasted on the underside of my mind.