src/HOL/Mirabelle/Tools/mirabelle_sledgehammer.ML

     val lam_trans = AList.lookup (op =) args lam_transK
     val uncurried_aliases = AList.lookup (op =) args uncurried_aliasesK
     val e_selection_heuristic = AList.lookup (op =) args e_selection_heuristicK
     val term_order = AList.lookup (op =) args term_orderK
     val force_sos = AList.lookup (op =) args force_sosK
-      |> Option.map (curry (op <>) "false")
+      |> Option.map (curry (<>) "false")
     val dir = AList.lookup (op =) args keepK
     val timeout = Mirabelle.get_int_setting args (prover_timeoutK, 30)
     (* always use a hard timeout, but give some slack so that the automatic
        minimizer has a chance to do its magic *)
     val preplay_timeout = AList.lookup (op =) args preplay_timeoutK