On Fri, 3 Nov 2006 roconnor@theorem.ca wrote:
On Wed, 1 Nov 2006, Henning Thielemann wrote:
On Wed, 1 Nov 2006 roconnor@theorem.ca wrote:
I've removed the controvertial isLeft, fromLeft, isRight, fromRight from the trac, and added lefts and rights. The controvertial additions can be put in a new trac. Let us focus on the the noncontrovertial additions first.
I've also renamed splitEithers into unzipEithers, which I think is better.
What was the reason against 'partitionEither' ? 'unzip' suggests there is also a 'zip'.
I have attached a new patch to the trac that now uses the identifier partitionEithers.
Sorry for being so inconstant. The more I thought about it, I found that unzipEither is the better choice. Since 'partition' takes a function, which decides, where an element should go, 'partitionEither' should also get such an argument: partitionEither :: (a -> Either b c) -> [a] -> ([b], [c]) partitionEither f = unzipEither . map f unzipEither :: [Either b c] -> ([b], [c]) I can imagine a 'zipEither' zipEither :: [Bool] -> [b] -> [c] -> [Either b c] zipEither = zipWith3 (\l r -> bool (Left l) (Right r)) with the recently proposed if-then-else replacement 'bool' http://www.haskell.org/pipermail/haskell-prime/2006-October/001803.html but maybe it is too simple, in order to be added to Data.Either. Analogously I suggest partitionMaybe :: (a -> Maybe b) -> [a] -> ([a], [b]) or partitionMaybe :: (a -> Maybe b) -> [a] -> ([b], [a]) where the parameter order of the second function is closer to 'partition' and is suitable for use in the State monad. A similar naming question arose with respect to Data.Map functions recently: http://www.haskell.org/pipermail/libraries/2006-August/005667.html