compiler exception when -> is used instead of => in instance definition
When running ghci on the attached file, the following exception is raised:
*** Exception: compiler/rename/RnSource.lhs:430:14-81: Irrefutable pattern failed for pattern Data.Maybe.Just (inst_tyvars,
_,
SrcLoc.L _ cls,
_)
It seems to stem from accidentally using -> instead of => in the following instance definition:
instance (ListConcat xs ys zs) -> ListConcat (x ::: xs) ys (x ::: zs)
where listConcat = undefined
Trac metadata
Trac field | Value |
---|---|
Version | 7.4.2 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Compiler |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | |
Operating system | |
Architecture |