EXTEND
      Pcaml.expr: AFTER "apply"
      [[ e1 = SELF; e2 = SELF ->
          match e1 with
          [ <:expr< fun $x$ -> $e$>> -> <:expr< (let $x$ = $e2$ in $e$)>>
          | _ ->
              match Pa_o.constr_expr_arity _loc e1 with
              [ 1 -> <:expr< $e1$ $e2$ >>
              | _ ->
                  match e2 with
                  [ <:expr< ( $list:el$ ) >> ->
                    List.fold_left (fun e1 e2 -> <:expr< $e1$ $e2$ >>) e1 el
                  | _ -> <:expr< $e1$ $e2$ >> ] ] ]]];
END;