[vats]

SICP language in racket lacks 1+ and -1+ (increment and decrement), last I checked. So it does still need some modification.

[soegaard]

Are those actually used in the book?

But if needed, the user can write:

    (define (1+ x) (+ x 1))
    (define (1- x) (- x 1))

Although, I think, add1 and sub1 are more common nowadays.

[jgwil2]

Pretty sure that example comes from the first edition. #lang sicp is made to work with the second edition I assume.