I'm working my way through SICP, using both the Ableson/Sussman lectures and the Berkeley 61A lectures, which are far more my speed. I'd like to do some of the Berkeley homework, but need the definitions for sentence, butfirst, butlast and so forth. It looks like at one time there was a simply scheme language built in to Dr. Scheme, but version 4.1.5, the most recent, doesn't have it. From Planet PLT I thought I could simply add (require (planet "simply-scheme.ss" ("dyoo" "simply-scheme" 1 0))) in my definitions window. I get
require: PLaneT
could not find the requested package: Server had no matching package:
No package matched the specified criteria
I tried grabbing the simply.scm file from here and pasted it into my Dr Scheme definitions window, but it doesn't work:
In Advanced Student mode, I get read: illegal use of "."
For the line (lambda (string . args) in the following code.
(define whoops
(let ((string? string?)
(string-append string-append)
(error error)
(cons cons)
(map map)
(apply apply))
(define (error-printform x)
(if (string? x)
(string-append "\"" x "\"")
x))
(lambda (string . args)
(apply error (cons string (map error-printform args))))))
In R5RS I get set!: cannot mutate module-required identifier in: number->string (line 7 of the following code)
(if (char=? #\+ (string-ref (number->string 1.0) 0))
(let ((old-ns number->string)
(char=? char=?)
(string-ref string-ref)
(substring substring)
(string-length string-length))
(set! number->string
(lambda args
(let ((result (apply old-ns args)))
(if (char=? #\+ (string-ref result 0))
(substring result 1 (string-length result))
result)))))
'no-problem)