Abstract Collections vs. FunDeps
dpt at lotus.bostoncoop.net
Sat Apr 3 10:12:52 EST 2004
On Fri, Apr 02, 2004 at 11:21:05AM +0200, Robert Will wrote:
> 1. Left-Single FunDeps are Syntactic Sugar for Constructor Classes
I think you should try writing programs a little before making such
broad claims... I was convinced when I read this, but then someone in
tried actually doing it, and ran into some trouble; see the second
half of the message. I don't know how to make the "Constructor Class"
version of the program work without '-fallow-undecidable-instances'.
> 3. Parametric Type Classes are Normalised FunDeps
> Classes with only one FunDep are necessarily in normal form. I don't
> want to consider transforming class declarations to normal form (no
> idea what that would mean...), just this: if we use a parametric type
> class of the form "class a \elem C b where" ('a' and 'b' sets of
> variables) then this corresponds just to a FunDep in normal form.
> Non-normal-form FunDeps can't be expressed with Parametric Type
I have no idea what you mean here. "class a \elem C b where" doesn't
look like Haskell to me. What is a parametric type class? Could you
expand a little?
(And maybe we should move this discussion to haskell-cafe, since it's
very off-topic for the libraries list and other people might be
interested. Maybe you could repost the parent there as an
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