What am I doing wrong in this Scheme statement?

Started by Alpha_ProgDes, Jan 14 2013 02:10 PM

Scheme Racket cond

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#1 Alpha_ProgDes Crossbones+ - Reputation: 3304

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Posted 14 January 2013 - 02:10 PM

(Note to Mods/Staff: Wasn't there a Functional or Lisp Prefix in the list before?)

(define (subtract-1 n)
  (string-append "Number is: " (number->string n))
  (cond
    [(= n 0) "All done!"]
    [else (subtract-1(- n 1))]))

I keep getting the error: define: expected only one expression for the function body, but found 1 extra part. I'm not understanding why I'm getting this.

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#2 rnlf Members - Reputation: 736

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Posted 14 January 2013 - 02:14 PM

I did never write a lot of scheme, but it looks to me like you have one closing parenthesis to much in line 2.

#3 swiftcoder Senior Moderators - Reputation: 4741

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Posted 14 January 2013 - 03:55 PM

rnlf is correct - i'd advise you switch to an editor with better brace-highlighting.

The interpreter is seeing '(string-append "Number is: " (number->string n))' as a complete statement (because it is), with the cond expression incorrectly trailing afterwards.

(Note to Mods/Staff: Wasn't there a Functional or Lisp Prefix in the list before?)

For some reason it wasn't enabled in For Beginners (only in General/Game Programming). I have enabled both prefixes in For Beginners.

Edited by swiftcoder, 14 January 2013 - 03:59 PM.

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