evaluate-jump-list.scm

#! /usr/bin/env guile -s !#
; guile needs the bash script comment closed

; saves an anonymous lambda later
(define inc (lambda (x) (+ x 1)))

; guiles list-set! function updates a list inplace but I want it to be immutable
; so I can use the old value from the list
(define (update-list lst index func)
	(update-list-rec lst index func 0))

; classic recursive func definition, should probably do it inside of the
; api func definition
(define (update-list-rec lst index func count)
	(cond
		((eq? '() lst) lst)
		((= index count)
			(cons (func (car lst)) (cdr lst)))
		((> index count)
			(cons
				(car lst)
				(update-list-rec
					(cdr lst)
					index
					func
					(+ count 1))))))

(define (jump-list lst)
	(jump-list-rec lst 0 0))

(define (jump-list-rec lst index count)
	(cond
		((eq? '() lst) -1)
			((> index (- (length lst) 1)) count)
		(else (jump-list-rec
			(update-list lst index inc)
			(+ index (list-ref lst index))
			(+ count 1)))))

; ommit a tone of numbers because...
(define program (list 0
2
0
...
-34))

(display (jump-list program))