On Wed, Oct 27, 2004 at 04:56:26PM +0900, Stijn De Saeger wrote:
Hi all,
I'm new to this list, as well as to haskell, so this question probably has "newbie" written all over it.
Not really.
I'm thinking of a way to represent a set of reals, say the reals between 0.0 and 1.0. Right now I am just using a pair of Float to represent the lower and upper bounds of the set, but i have this dark throbbing feeling that there should be a more haskellish way to do this, using laziness. List comprehensions are out it seems, because they increment with integer steps... (obviously). In other words, 0.5 `inSet` (Set [0.0..1.0]) returns False.
Yes. That is because lists are either finite or countable, whereas any interval of the reals is uncountable. Not all is lost however.
I'm sure someone must have hit this problem before me and found a way around it. any suggestions greatly appreciated,
Well, there have been multiple forays into exact real arithmetic, with implementations in Haskell. One that may well be of use to your problem is David Plume's calculator for exact real number computation. Google for it, and for `interval arithmetic'. Doei, Arthur. -- /\ / | arthurvl@cs.uu.nl | Work like you don't need the money /__\ / | A friend is someone with whom | Love like you have never been hurt / \/__ | you can dare to be yourself | Dance like there's nobody watching