Hmm. Seems I missed sending this to haskell-prime.
Sorry.
/Henrik
--
Henrik Nilsson
School of Computer Science and Information Technology
The University of Nottingham
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--- Begin Message ---
Dear all,
Simon PJ wrote:
> Now, someone can try to define a conservative version of FDs, as has
> been suggested; perhaps it could even be kind-of-isomorphic to
> associated types. Perhaps something *very* conservative would be
> enough for most applications. (It would hurt to standardise FDs if we
> think we're going to discard them subsequently, but if the spec was
> somewhat crisp maybe it would not hurt too much.)
What about the "FD Conditions" as defined in the paper by Sulzman, Duck,
Peyton-Jones and Stuckey you referred to? (Mark Jones original
conditions + a so called "bound variable condition").
If those conditions are imposed, one gets sound, complete,
and decidable type inference according to the said paper.
I had a quick look at the monadic libraries and a vector space class in
Yampa, and my impression is that the FDs used there would be compatible
with the FD conditions. But I emphasize that's just an impression.
Or are the FD conditions considered too restrictive?
Clearly, as exemplified in the above paper, they do rule out a number of
reasonable programs. But as long as the adopted version of FDs
allow the basic usage of FDs for applications like monad transformers,
I don't think I personally would be too unhappy.
Best,
/Henrik
--
Henrik Nilsson
School of Computer Science and Information Technology
The University of Nottingham
[EMAIL PROTECTED]
--- End Message ---
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