[racket] lazy racket

Hi,

I'd like to tweak Lazy Racket such that the top-level interactions in the REPL always use `!!' (recursive force), in order to mimic Haskell's behavior as close as possible.

If someone can help me in the very brief term, I would really appreciate it (I plan to start teaching on laziness using Lazy Racket tomorrow).

Thanks in advance!

-- Éric

PS: Eli told me of some parameter that controls this behavior. I think it is `toplevel-forcer', but a) I'm not sure, b) even if I hack it manually (edit lazy.rkt), it does not work:

;; parameter is properly set to `!!'
> (toplevel-forcer)
#<procedure:!!>

> ones
#<promise:ones>

> (!! ones)
#0='(1 . #0#)

I'd like the following behavior:
> ones
#0='(1 . #0#)