scheme_examples.scm

; extra all list elements in a list
(define (extract-list lst)
  (cond ((null? lst) lst)
    ((list? (car lst)) (cons (car lst) (extract-lists (cdr lst))))
    (else (extract-list (cdr lst))
    )
 )
    
    ; return number of even integers
(defin (count-even lst)
    (cond ((null? lst) 0)
    ((even? (car lst))  (+ 1 ( count-even (cdr lst))))
    (else (count-even (cdr lst))
    )
)
    
    ; create pairs from elements l1 l2
(define (create-pairs l1 l2) 
    (cond ((null? l1) l1)
      ((not (= (length l1) (length l2))) ())
      (else (cons (list (car l1) (car l2))
      (create-pairs (cdr l1) cdr l2))))
    )
)
  
  ;    Makes a new list with every combination of the 2 list
  (define (product lst1 lst2)
    (cond
        ((null? lst1) ())
        ((null? lst2) ())
        (else (append (pair-elem (car lst1) lst2) (product (cdr lst1) lst2)))    
    )
)
(define (pair-elem atm lst)
    (cond 
        ((nulL? (cdr lst)) (list atm (car lst)))
        (else (list (list atm (car lst)) (pair-elem atm (cdr lst))))
    )
)
  
  
  ;  Removes duplicates from a list
  
  (define (remove-el el lst)
    (cond ((null? lst)  lst)
          ((equal? el (car lst)) (remove-el el (cdr lst)))
          (else (cons (car lst) (remove-el el (cdr lst))))
          )
    )
(define (remove-dups lst)
  (cond ((null? lst) lst)
        ((member (car lst) (cdr lst))
         (cons (car lst) remove-dups (remove-el (car lst) (cdr lst))))))
  (else (cons 
         
         
         ; fib recursive
(define (fib atm) (rec-fib 1 0 atm))
(define (rec-fib n m atm) 
    (if (equal? atm 0) m (rec-fib (+ n m) n (- atm 1)))
)