panic using type families and type classes
I got a panic while trying to compile some code using type families:
ghc-6.9.20080528: panic! (the 'impossible' happened)
(GHC version 6.9.20080528 for i386-apple-darwin):
urk! lookup local fingerprint
I can't post the code that caused that (yet) but when I was trying to distill it down to its essence for a bug report, I got a different panic:
ghc-6.9.20080528: panic! (the 'impossible' happened)
(GHC version 6.9.20080528 for i386-apple-darwin):
Prelude.head: empty list
I've attached the code that caused it. I know the code might not be 100% correct, and it's a bit long, but I think it might help some.