tcfail017.hs:10:
- Could not deduce `C [a]'
- (arising from an instance declaration at tcfail017.hs:10)
- from the context: (B a)
+ Could not deduce `C [a]' from the context: (B a)
Probable cause: missing `C [a]' in instance declaration context
or missing instance declaration for `C [a]'
- When checking the superclasses of an instance declaration
+ arising from an instance declaration at tcfail017.hs:10
Compilation had errors