Re: [Haskell-beginners] Using IORef

On Mon, Jan 6, 2014 at 10:15 PM, Courtney Robinson wrote:

On Tue, Jan 7, 2014 at 3:03 AM, Brandon Allbery wrote:

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behind

Oh I see, thanks for the info. really helpful. It brings about another question now.

How is newIORef meant to be used so that I only have a single IORef?

The Haskell way is to carry such things implicitly in a State or Reader monad; since the IORef itself doesn't change, and you need the IO monad around anyway to actually use it, you would use a ReaderT IORef IO and then use ask >>= liftIO . readIORef to get the value and similar to write or modify it. (Commonly one uses a type or newtype+newtype deriving to make one's own monad combining them.) -- brandon s allbery kf8nh sine nomine associates allbery.b@gmail.com ballbery@sinenomine.net unix, openafs, kerberos, infrastructure, xmonad http://sinenomine.net