On Friday 23 April 2004 20:05, S. Alexander Jacobson wrote: > Yes, that makes sense, but I'm ok with passing in > an identity. I'd like a function like this: > > newChanSafe::Identity -> Chan a > type Identity = Double -- or whatever
As Nick observes, using this function would require you to pass around a supply of unique Identitys. If we assume you're going to have to do this, why not simplify things and pass around a list of newChans: type Identity = Chan Int withChan :: (Identity -> a) -> [Identity] -> (a,[Identity]) ... You can use unsafeInterleaveIO to create a lazy list of channels. Better yet, you can use unsafeInterleaveIO to create a lazy tree of channels so that splitting the supply is efficient. One minor detail left as an exercise: my definition of Identity is monomorphic but you probably want them to be polymorphic. This is a bit tricky to fix and will require a monad (or equivalent) to ensure that you don't allocate the same chan twice and then use it at different types. (Probably requires unsafeCast too.) -- Alastair Reid _______________________________________________ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
