DrRacket: function call: expected function, given: (list ...)

Asked Mar 14 '18 at 13:00

Active Mar 14 '18 at 13:00

Viewed 67 times

This is a Code, which 'removes' duplicates:

(define (positions list)
   (sort (foldl (lambda (x y) (if (not (member? x y)) (append (list x) y) y)) empty list) <))

When I tested this:

(positions (list 3 4 4 5 8 9 4 1 2 9))

I get an error function call: expected function, given: (list 3 4 4 5 8 9 4 1 2 9)

But when I replace (list x) with (cons x '()) it works. Why? Aren't both the same?

asked Mar 14 '18 at 13:00

jdoe

1

I believe that `list` is a built-in function supplied by scheme. It looks like you are shadowing that with your own parameter `list` in your function. Try renaming that to `l` or something else. – Hunter McMillen Mar 14 '18 at 13:04
It worked. Thank you. – jdoe Mar 14 '18 at 13:09
Look at the part "shadowing procedures" – Sylwester Mar 14 '18 at 18:00

0 Answers0