[bitc-dev] RE: Type Classes and Specialization
Jonathan S. Shapiro
shap at eros-os.org
Mon Jul 25 11:11:39 EDT 2005
On Sun, 2005-07-24 at 22:16 -0700, Mark P Jones wrote:
> Some implementations of Haskell support "overlapping" instances, which
> means that the compiler allows instances to overlap with one another...
> instance TC [a] where ...
> instance TC [Char] where ...
So we have established from another email that if TC [a] has been
imported, but TC [Char] has not, it is possible to see situations where
we might have a something of type [Char] get treated as something of
It appears to me that in order for this situation to occur, we must have
declarations in scope for both TC and also for Char.
Q1: Am I correct?
If so, then this provides sufficient information for us to know that we
are *looking* for a resolution specialized for Char, but it is *not*
always sufficient to tell us what the best (globally) specialization
would be. It may, however, be sufficient to let us generate a link-time
error if we are a bit clever with name mangling.
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