[m-dev.] for review: rewrite of check_typeclass.m

[Peter Schachte]

Hi DJ,

On Wed, 20 May 1998, David Glen JEFFERY wrote:

> A re-work on check_typeclass.m. Now, rather than the ad-hoc approach of 
> checking each method of each instance declaration for *exact* type and mode
> correctness, we generate a new predicate that gets inserted into the HLDS.
> This predicate is checked for type, mode, uniqueness and determinism 
> correctness in the appropriate compiler passes.

Does this mean that type class methods can now be impure or semipure?  That
should probably be allowed.  Instances should be checked that the
corresponding predicates are no less pure than the class specifies (but more
pure should be ok, I think).


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