[plt-scheme] imperative vs functional

I made a little program with DrScheme and world.ss teachpack

my goal is to try to use the functional programming concept mixin
object oriented programming
I 'm french beginner in Scheme...

source code (imperative OO) is here :
http://jvjulien.free.fr/site/scheme/ping-pong/ping-pong.ss

and the equivalent (functional / imperative OO) code test is here :
http://jvjulien.free.fr/site/scheme/ping-pong/ping-pong-ft.ss

the second version obliges methods to create a new object instance at
each call. so it's necessary to initialize each fields of this new
object... if it's a complex class, that does not seem very
effective...

exist there a method to reconcile the two approaches (OO and
functional) ?
thanks