+mkCanonicalFEVs :: Bag FlavoredEvVar -> TcS WorkList
+mkCanonicalFEVs = foldrBagM canon_one emptyWorkList
+ where -- Preserves order (shouldn't be important, but curently
+ -- is important for the vectoriser)
+ canon_one fev wl = do { wl' <- mkCanonicalFEV fev
+ ; return (unionWorkList wl' wl) }
+
+mkCanonical :: CtFlavor -> EvVar -> TcS WorkList