[Haskell-cafe] (a -> [b]) vs. [a -> b]
J. Garrett Morris
trevion at gmail.com
Fri Feb 2 15:33:38 EST 2007
Uh, apologies. I got confused between reading your post and playing
for a while, and answered the wrong question.
On 2/2/07, J. Garrett Morris <trevion at gmail.com> wrote:
> On 2/2/07, Chad Scherrer <chad.scherrer at gmail.com> 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'))
> 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.
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