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

[Martin Sulzmann]

We're also looking for (practical) examples of "multi-range" functional 
dependencies

class C a b c | c -> a b

Notice that there are multiple (two) parameters in the range of the FD.

It's tempting to convert the above to

class C a b c | c -> a, c -> b

but this yields a weaker (in terms of type improvement) system.

Thanks,
     Martin



Tom Schrijvers wrote:
> Hello,
>
> I'm looking for practical examples of non-full functional dependencies 
> and would be grateful if anyone could show me some or point to 
> applications using them.
>
> A non-full functional dependency is one involves only part of the 
> parameters of a type class. E.g.
>
>     class C a b c | a -> b
>
> has a non-full functional dependency a -> b which does not involve c.
>
> Thanks,
>
> Tom
>
> -- 
> Tom Schrijvers
>
> Department of Computer Science
> K.U. Leuven
> Celestijnenlaan 200A
> B-3001 Heverlee
> Belgium
>
> tel: +32 16 327544
> e-mail: tom.schrijvers at cs.kuleuven.be
> url: http://www.cs.kuleuven.be/~toms/
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