[Haskell-cafe] looking for examples of non-full Functional Dependencies

Hans Aberg haberg at math.su.se
Fri Apr 25 09:20:27 EDT 2008

On 25 Apr 2008, at 14:20, Tom Schrijvers wrote:

> Prolog works under the assumption of a closed world. That's  
> contrary to the open world view of regular type classes. So these  
> aren't the intended semantics.

By which I gather you mean the interpretation of ":-" as logical  
connective "=>" rather than provability "|-"?

My point, though, was to interpret
   class a b | a -> b
as a functional dependency b = b(a) rather than as
   D a b, D a c ==> b=c
Thus trying to eliminate the use of "=".

Might that be exploited in the type theory context?


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