Overloaded record fields
anthony_clayden at clear.net.nz
Thu Jun 27 13:43:43 CEST 2013
> Adam Gundry <adam.gundry <at> strath.ac.uk> writes:
> I've started to document the plan on the GHC wiki:
Thank you Adam, (Simon)
I like the approach for Representation hiding. (That was something I was
particularly trying to preserve out of H98 records.)
At first I was worried this would involve 'scoped' instances -- which
seems a wild departure.
But I see in the 'Multiple modules' section that you're generating
instances on-the-fly. So I agree that option (2) looks best.
As I understand it, this means that the extensions switched on in the
importing module is all we have to worry about, not what extensions
applied where the data type is declared.
So for backward compatibility, I can import historic Library L ( R(x) )
which knows nothing about the new stuff. And in my module (with the
extension on) declare data type T with field x, and not have a clash of
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