Just (abs_vars, _) -> abs_vars
Nothing -> [v]
- add_tyvars v | isId v = v : varSetElems (idFreeTyVars v)
- | otherwise = [v]
+ add_tyvars v = v : varSetElems (varTypeTyVars v)
-- We are going to lambda-abstract, so nuke any IdInfo,
-- and add the tyvars of the Id (if necessary)