[mercury-users] Modules, Submodules and Instances.

[David Glen JEFFERY]

On 02-Feb-1999, Fergus Henderson <fjh at cs.mu.OZ.AU> wrote:
> > > > 
> > > > 	1.  Disallow instance declarations for abstract equivalence types.
> > 
> > Oh God no!
> 
> Well, that's the solution that Haskell adopts, and Haskell programmers
> seem to tolerate it, so it can't be *that* bad.

Yeah... but they're a little slow over there in Haskell-land. ;-)

> 
> The final problem, of course, is just that it would not be trivial to
> implement.  So for the time being at least, I am still inclined to go
> with the conservative (and easy to implement) solution:
> 
> 	1.  Disallow instance declarations for abstract equivalence types.


I think that this conservative approach is the best one at this stage. I would
not like to define (or implement!) a fairly complicated transformation in
order to get (the semantics) of this to work at this stage.

> We can reconsider this at a later date.

Indeed.



dgj
-- 
David Jeffery (dgj at cs.mu.oz.au) |  Marge: Homer, is this how you pictured
PhD student,                    |         married life?
Dept. of Comp. Sci. & Soft. Eng.|  Homer: Yup, pretty much... except we
The University of Melbourne     |         drove around in a van solving
Australia                       |         mysteries.