How to get the cudder of a list with foldr?

I have managed to write a cudder that requires equality checks... but that's not good enough -- there should be no required functions :/

[def]foldr
     [ls]f x list[/ls]
     [if][empty][var]list[/var][/empty]
         [var]x[/var]
         [apply][var]f[/var]
                [car][var]list[/var][/car]
                [foldr][var]f[/var]
                       [var]x[/var]
                       [cudder][var]list[/var][/cudder]
                [/foldr]
         [/apply]
     [/if]
[/def]
Fixed.