GHC Proposal #371 requires TypeOperators to use type equality a~b. The following lines are affected:
instance e ~ SomeException => MonadThrow (Either e) where
instance e ~ SomeException => MonadCatch (Either e) where
instance e ~ SomeException => MonadMask (Either e) where
GHC Proposal #371 requires
TypeOperators
to use type equalitya~b
. The following lines are affected:The fix is to simply enable the extension.