On Mon, Dec 28, 2009 at 10:32 PM, Jonathan Fischoff
Hi, I would to create a list of tuples (or something similar) of invertible functions [((a -> b), (b -> a)), ((b -> c), (c -> b)), .... Such that I could call forward invertibleFuctionList domainValue = ? -- composite all the functions backward invertibleFuctionList rangeValue = forward (reverse invertibleFuctionList) rangeValue -- or something similar
I would also like to concat them. This sounds like a job for GADT that someone might have already tackled. Any ideas?
It looks like the thrist package should help you out: http://hackage.haskell.org/cgi-bin/hackage-scripts/package/thrist You could define some sort of type Iso: data Iso a b = Iso (a -> b) (b -> a) And then build a Thrist and fold over it, the functions forward and backwards can both be implemented with right-folds.