Help understanding Specialise.lhs

David Feuer david.feuer at
Mon Oct 20 11:53:11 UTC 2014

On Oct 20, 2014 5:05 AM, "Simon Peyton Jones" <simonpj at> wrote:
> I’m unclear what you are trying to achieve with #9701.  I urge you to
write a clear specification that we all agree about before burning cycles
hacking code.

What I'm trying to achieve is to make specialization work in a situation
where it currently does not. It appears that when the type checker
determines that a GADT carries a certain dictionary, the specializer
happily uses it *even once the concrete type is completely known*. What we
would want to do in that case is to replace the use of the GADT-carried
dictionary with a use of the known dictionary for that type.

> There are a lot of comments at the top of Specialise.lhs.  But it is, I’m
afraid, a tricky pass.  I could skype.

I would appreciate that. What day/time are you available?
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <>

More information about the ghc-devs mailing list