At 09:14 18/11/03 +1300, Tom Pledger wrote:
Graham Klyne writes: : | Below is some code I have written, which works, but I'm not sure | that it's especially efficient or elegant. Are there any published | Haskell libraries that contain something like this?
Hi.
Partially ordered sets are in cahoots with lattices, so you may be interested in http://www.cse.ogi.edu/~mpj/pubs/lattices.html .
That might be interesting... is full paper available online? (I don't have easy access to a serious technical library.)
And here's some off-the-cuff feedback...
How about using Maybe Ordering, instead of a new data type? (As in http://www.mail-archive.com/haskell@haskell.org/msg05635.html)
Duh. That sounds like an excellent idea - I knew there was a reason for posing dumb questions like these!
Instead of hard-wiring Maybe into the element type in dropSubsumed, how about passing in a partial comparison function?
dropSubsumedBy :: (a -> a -> Maybe Ordering) -> [a] -> [a]
Yes, I agree that would be neater. (Though I was aware that this code was too specialized in many ways. I have noticed that it's often easier (for me) to code for a specific situation and then generalize the resulting code, than to go immediately for the general case. Haskell seems to be particularly well suited to factoring out the type-specific bits in this way, I think because it's often easy to parameterize any piece of code as a higher order function.) Thanks for your insights! #g ------------ Graham Klyne For email: http://www.ninebynine.org/#Contact