Re: Please apply the comparison function given to nubBy to elements of the list in the order in which they occur in the list.

In case you further want to discuss this, I've re-opened http://hackage.haskell.org/trac/ghc/ticket/2528#comment:10 So, I'm against your proposal, Cale, but suggest that you revert the order in your example (if you want to exploit this behavior). Cheers Christian Am 08.09.2011 02:07, schrieb

Re: Please apply the comparison function given to nubBy to elements of the list in the order in which they occur in the list.

Am 20.09.2011 20:21, schrieb Edward Kmett: [...] I would suggest you rephrase this as a formal proposal, then I can happily vote +1. Seeing the wonderful interrelation between elem, nub, nubBy and i.e. unionBy eq xs ys = xs ++ foldl (flip (deleteBy eq)) (nubBy eq ys) xs intersectBy eq

Re: Please apply the comparison function given to nubBy to elements of the list in the order in which they occur in the list.

Looking at the code of nubBy http://www.haskell.org/ghc/docs/latest/html/libraries/base-4.4.0.0/src/Data-List.html#nubBy nubBy :: (a - a - Bool) - [a] - [a] #ifdef USE_REPORT_PRELUDE nubBy eq [] = [] nubBy eq (x:xs) = x : nubBy eq (filter (\ y - not (eq x

Re: Please apply the comparison function given to nubBy to elements of the list in the order in which they occur in the list.

If this is a _proposal_ to change ghc's non-Report-compatible Data.List implementation to match the behaviour of the Report implementation, then count me as a +1. I think an important convention when it comes to higher order functions on lists is that to the extent which is possible, the

Re: Please apply the comparison function given to nubBy to elements of the list in the order in which they occur in the list.

Apologies for responding to myself, but the difference between the REPORT_PRELUDE and the ghc implementation also applies to elem and notElem. #ifdef USE_REPORT_PRELUDE elem x = any (== x) notElem x = all (/= x) #else elem _ [] = False elem x (y:ys) =