Scheme function that sum number u and list x u+x1+x2

Question

Im new to Scheme and trying to make function that is (in f u x), u is integer, x is a list and f binary function. The scheme expression (in + 3 '(1 2 3)) should return 3+1+2+3=9.

I have this but if i do (in + 3 '(1 2)) it return 3 not 6. What am i doing wrong?

(define (in f u x)
  (define (h x u)
    (if (null? x)
        u
        (h (cdr x) (f u (car x)))))
  (h x 0))

I recommend commenting your code. Then it would be easy to compare the comments with what the code actually does to see where it went wrong. — Gabe, Sep 24 '11 at 14:38

score 2 · Accepted Answer · edited May 23 '17 at 09:59

2

From what I understand of what your in function is supposed to do, you can define it this way:

(define in fold)   ; after loading SRFI 1

:-P

(More seriously, you can look at my implementation of fold for some ideas, but you should submit your own version for homework.)

edited May 23 '17 at 09:59

Community

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answered Sep 24 '11 at 14:47

C. K. Young

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Thanku, i will not copy paste you solution, not what i do, just wanted to see if any one could give me hint or give me ideas of how i can solve this problem. You did Thanks. – Sep 24 '11 at 15:27

Scheme function that sum number u and list x u+x1+x2

1 Answers1