This is all expected behavior. GHC's lazy overlap checking for class instances
simply cannot apply to type families -- it would be unsound. I'm afraid I don't
see what can be improved here.
Richard
On Jun 6, 2015, at 2:04 AM, AntC anthony_clay...@clear.net.nz wrote:
From: AntC
Date:
Hi,
AntC's f can be done without -XOverlappingInstances
http://lpaste.net/7559485273839501312, using the trick didn't work in
#9918. I'm not sure extra syntax is justified to clean up this rare case.
Regards,
Adam
On Sun, Jun 7, 2015 at 11:12 AM, Dan Doel dan.d...@gmail.com wrote:
It
That's right. You're suggesting instance chains [1][2].
[1]: https://ghc.haskell.org/trac/ghc/ticket/9334
[2]: http://web.cecs.pdx.edu/~mpj/pubs/instancechains.pdf
Richard
On Jun 7, 2015, at 11:12 AM, Dan Doel dan.d...@gmail.com wrote:
It seems to me the problem is that there's no way to
It seems to me the problem is that there's no way to define classes by
consecutive cases to match the family definitions. I don't know what a good
syntax for that would be, since 'where' syntax is taken for those. But it
seems like it would correspond fill the hole here.
On Sun, Jun 7, 2015 at
