How to delete an element from a list in scheme

Question

how to delete an element from a list ex:- list=[1 2 3 4]

I have come up with some code.I think I got wrong somewhere.

 (define delete item
   (lambda         


        

Answer 1

Shido Takafumi wrote a tutorial about Scheme, Yet Another Scheme Tutorial. In chapter 7, exercise 1, the 3rd problem.

A function that takes a list (ls) and an object (x) as arguments and returns a list removing x from ls.

The author gave the solution code bottom of the page.

; 3
(define (remove x ls)
  (if (null? ls)
      '()
      (let ((h (car ls)))
        ((if (eqv? x h)
            (lambda (y) y)
            (lambda (y) (cons h y)))
         (remove x (cdr ls))))))

The code maybe difficult to comprehend for beginner. It's same as the code below.

(define (rm x ls)
  (if (null? ls)
      '()
      (if (eqv? x (car ls))
          (rm x (cdr ls))
          (cons (car ls)
                (rm x (cdr ls))))))

This can delete the same elements in list. :D