- -- For each AT argument compute the position of the corresponding class
- -- parameter in the class head. This will later serve as a permutation
- -- vector when checking the validity of instance declarations.
- setTyThingPoss (ATyCon tycon) atTyVars =
- let classTyVars = map fst tv_bndrs
- poss = catMaybes
- . map ((`elemIndex` classTyVars) . fst)
- $ atTyVars
- -- There will be no Nothing, as we already passed renaming
- in
- ATyCon (setTyConArgPoss tycon poss)
- setTyThingPoss _ _ = panic "TcIface.setTyThingPoss"
-