dr.racket

问题 I\'m trying with SICP and I got some code. So I started with: #lang scheme (word \'comp \'uter) Returned error: Function (word) undefined. Even if I tried to copy this into IDE(Run): (define word? (let ((number? number?) (symbol? symbol?) (string? string?)) (lambda (x) (or (symbol? x) (number? x) (string? x))))) Still the same. I think it may be certain problem with version of language or else. Above are from \"Simply Scheme\" and when I introduce code exactly in SICP: (define (sqrt x) (sqrt