Stephan Friedrichs wrote:
I'm sorry it took me so long to respond!
No worries :)
In conclusion: the ordering policy stuff should not be part of Data.Heap, this is a job for Data.Ord. This sounds really useful. How about you propose this to the base-package maintainers? :)
What, me? :D
Where? :)
Proposals for the base package go to libraries@haskell.org . A proposal is a darcs patch + a deadline. Unfortunately, ghc 6.8.* isn't yet available on Macports, I'd have to install 6.6.1 again on my wiped disk to get a haskell compiler and darcs. I'm currently leaning towards code like data OrdBy p a = OrdBy { unOrdBy :: a } instance Eq a => Eq (OrdBy p a) where (==) = (==) `on` unOrdBy data Reverse type Reversed a = OrdBy Reverse a instance Ord a => Ord (OrdBy Reverse a) where compare = flip $ comparing unOrdBy and probably another example for custom orderings. Do you now a good one? I'm not so happy about the names. In particular, I don't like unOrdBy , too much cAmelCase. Any other ideas? Maybe data Rearrange p a = Rearrange { unRearrange :: a } data ReOrd p a = ReOrd { unReOrd :: a } But I guess it can't be helped and it's not too bad either. The class constraint Ord (OrdBy p a) => will be common in user code, but it's a bit bulky for my taste. However, its main problem is that it's not Haskell98 :( A multi-parameter class (just like in the original heap-0.1) class OrdPolicy p a where ... instance OrdPolicy p a => Ord (OrdBy p a) where ... is shorter but not H98 either. The name could be a mot juste, too. class Rearranged p a where ... class Ord' p a where ... class OrdBy p a where ... -- clashes with the name of the type Regards, apfelmus