A slight variant:
let
__div = x: y: y x;
in
builtins.readDir "/etc" / builtins.attrNames / builtins.length
let
__mul = x: y: if builtins.typeOf y != "lambda"
then x y
else z: x (y z);
in
builtins.length * builtins.attrNames * builtins.readDir "/etc"
source:[spoiler]Add an infix reverse-application operator · Issue #2118 · NixOS/nix · GitHub