dr scheme, help!

[Mayer]

Is there anything I can type somewhere in Dr Scheme, that would let me
have gensym, set-car!, set-cdr!, error, format, etc -- Every one of
the language combinations I tried gives me some of these but not the
other.

Thanks,

Mayer

[Jean Guillaume Pyraksos]

#lang scheme
(require scheme/mpair) ; for mutable lists !

(printf "(gensym 'foo) --> ~a\n" (gensym 'foo))

(define L (mlist 'a 'b 'c 'd))
(printf "L --> ~a\n" L) ; {a b c d} and not (a b c d)
(set-mcar! L 'foo) ; no more set-car!
(printf "L --> ~a\n" L)

JG