Senaste senaste

;Problem 1

(define (atom? n)
  (if 
   (or (null? n) (pair? n) )
       #f
       #t))
      

;Problem 2

(define (count-list lst)
  (if (null? lst)
      0
      (+ 1 (count-list(cdr lst)))))

;Problem 3

(define (keep-if pred lat)
  (cond
    ((null? lat) '())
    ((pred (car lat))
      (cons (car lat) (keep-if pred (cdr lat))))
     (else (keep-if pred (cdr lat)))))

;Problem 4

(define (first-n numb-of-ele lst)
  (cond
    ((= numb-of-ele 0) '())
    ((<= (count-list lst) numb-of-ele) lst)
  (else (cons (car lst) (first-n (- numb-of-ele 1) (cdr lst))))))

;Problem 5

(define (range from to step)
  (if (> from to)
      '()
      (cons from (range (+ from step) to step))))

;Problem 6

;Iterative

(define (reverse-order lst)
  (define (reverse-iter lst fantasyswing)
    (if (null? lst)
        fantasyswing
        (reverse-iter (cdr lst) (cons (car lst) fantasyswing))))
  (reverse-iter lst '()))

;Linear Recursive

(define (reverse-order-2 lst)
  (if (null? lst)
      lst
     (append (reverse-order-2 (cdr lst)) (cons (car lst) ()))))

(define (my-append lst1 lst2)   
    (append (lst1 lst2)))
;Problem 7


(define (map-to-each funktion lst)
  (if (null? lst)
      '()
      (cons (funktion (car lst)) (map-to-each funktion (cdr lst)))))

;Problem 8

(define (count-all lst)
  (cond 
    ((null? lst) 0)
    ((list? (car lst)) (+ (count-all (car lst)) (count-all (cdr lst))))
      (else (+ 1 (count-all(cdr lst))))))

(define (keep-if-all pred lat)
  (cond
    ((if (atom? lat) '()
    ((list? (car lat)) (keep-if-all pred (car lat)))))
    ((pred (car lat))
     (cons (car lat) (keep-if-all pred (cdr lat))))
    (else (keep-if-all pred (cdr lat)))))

;Problem 9