On Thu, 21 Feb 2008, Roman Leshchinskiy wrote:
John Goerzen wrote:
2) Would it make sense to make ListLike, or something like it, part of the Haskell core?
I don't think ListLike is the right approach. It's basically a fairly arbitrary collection of functions. It would be preferable, IMO, to identify a small set of combinators which would allow most list/sequence functions to be implemented generically and efficiently. Personally, I'd go with something like streams (the stream fusion ones) but I'm biased, of course.
As long as it is only about speeding up list processing, one might also consider this as optimization problem. This could be handled without adapting much List based code in applications to a generic sequence class. That is, if I convert the result of a composition of list functions to a lazy ByteString, I tell the compiler that I don't need full laziness and the compiler can optimize, say ByteString.fromList . List.func1 . List.func2 . List.build to ByteString.func1 . ByteString.func2 . ByteString.build or even better ByteString.fusedFunc1Func2Build by some clever fusion framework. I think that a type class is easier to justify if it unifies data structures that are more different than just providing the same API with different efficiency.