> Basically, I have a signal processing loop, where values are passed > updated with a Maybe, representing whether there is or is not a change > to the value. I could use a single Maybe around the whole thing, but > that would require then re-updating a potentially large structure > entirely. I want to be able to build a combinator that can combine two > signal-fetching actions into a larger one: > > IO (Maybe a) -> IO (...) -> IO (Maybe a, (...)) > > and then an action that could, given the previous value: > (a, (...)) > > update any places in this chain of pairs where the Maybe is not Nothing.
Sounds like you want a generic diff: http://hackage.haskell.org/package/gdiff-1.0 Cheers, Sterl _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
