utils.scm

(define (value-at arr pos destination-pos)
  (if (null? arr)
    -1
    (if (eq? pos destination-pos)
      (begin
        (display (car arr))
        (car arr)
        )
      (value-at (cdr arr) (+ pos 1) destination-pos)
      )
    )
  )
(define (display-with-types-rec l first)
  (if first
    (if (pair? l)
      (display "(")
      )
    )
  (if (null? l)
    (display ") ")
    (if (number? l)
      (begin
        (if first
          (display "")
          (display " ")
          )
        (display l)
        (display "")
        )
      (if (string? l)
        (begin
          (if first
            (display "\"")
            (display " \"")
            )
          (display l)
          (display "\"")
          )
        (if (pair? (car l))
          (begin
            (display-with-types-rec (car l) #t)
            (display-with-types-rec (cdr l) #f)
            )
          (if (pair? l)
            (begin
              (display-with-types-rec (car l) first)
              (display-with-types-rec (cdr l) #f)
              )
            )
          )
        )
      )
    )
  )

(define (display-with-types l)
  (if (boolean? l)
    (if l
      (display "true")
      (display "false")
      )
    (display-with-types-rec l #t)
    )
  )
(define (delete-first item arr)
  (cond
    ((null? arr) '())
    ((equal? (car arr) item) (cdr arr))
    (else (cons (car arr) (delete-first item (cdr arr))))
    ))