[Haskell-cafe] Proposal: Instance apartness guards
anthony_clayden at clear.net.nz
Wed Nov 8 09:29:57 UTC 2017
Surprisinlgy little comment on this proposal.
Perhaps it landed when yous were busy elsewhere.
I'd like to push it to the committee soon;
this is an invitation for more feedback.
Richard E wrote a nice brief summary
----- Original Message Follows -----
> After years of pondering this idea (in various forms),
> and several rounds of discussion on several forums,
> I've written it up.
> "This proposal tackles the thorny topic of Overlapping
> for both type classes and Type Families/Associated types,
> by annotating instance heads with type-level apartness
> Type-level disequality predicates appear in Sulzmann &
> Stuckey 2002;
> in the type-level case selection in HList 2004;
> and in various guises in Haskell cafe discussions in
> following years.
> This proposal builds on the apartness testing implemented
> as part of the Closed Type Families work."
> All feedback welcome.
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