-match_eq_string :: [Expr CoreBndr] -> Maybe (Expr CoreBndr)
-match_eq_string [Var unpk1 `App` Lit (MachStr s1),
- Var unpk2 `App` Lit (MachStr s2)]
+match_eq_string :: IdUnfoldingFun -> [Expr CoreBndr] -> Maybe (Expr CoreBndr)
+match_eq_string _ [Var unpk1 `App` Lit (MachStr s1),
+ Var unpk2 `App` Lit (MachStr s2)]