GHC accepts overly general instance sigs
{-# LANGUAGE InstanceSigs #-}
data I a = MkI a
instance Functor I where
fmap :: (a -> b) -> f a -> f b
fmap = undefined
is accepted when the type is too general, even things like:
fmap :: (a -> b) -> f a -> g b
-- &
fmap :: whoami
are accepted
Trac metadata
Trac field | Value |
---|---|
Version | 8.1 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Compiler |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | |
Operating system | |
Architecture |