[Haskell-cafe] Re: coherence when overlapping?

[Tom Schrijvers]

On Thu, 13 Apr 2006, Martin Sulzmann wrote:

>
> I believe that GHC's overlapping instance extensions
> effectively uses inequalities.
>
> Why do you think that 'inequalities' model 'best-fit'?
>
> instance C Int      -- (1)
> instance C a        -- (2)
>
> under a 'best-fit' instance reduction strategy
> we would resolve C a by using (2).

Claus used the term best-fit, and what was meant is exactly the same as 
what you mean, i.e. a delayed until sufficiently instantiated best-fit 
rather than an immediate best fit.

--
Tom Schrijvers

Department of Computer Science
K.U. Leuven
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tel: +32 16 327544
e-mail: tom.schrijvers at cs.kuleuven.be