#!/usr/bin/guile \
-e main -s
!#
;;; Copyright 2005 Daniel Cer (daniel.cer@cs.colorado.edu)
;;;
;;; This work is licensed under the Creative Commons Attribution-NonCommercial-
;;; ShareAlike License. To view a copy of this license, visit 
;;; http://creativecommons.org/licenses/by-nc-sa/2.5/ or send a letter to 
;;; Creative Commons, 543 Howard Street, 5th Floor, San Francisco, California, 
;;; 94105, USA.

(define (fibonacci n) (if (<= n 0) -1 
(do ((fib 1 (+ fib prev_fib)) (prev_fib 1 fib) (i 2 (+ i 1)) ) 
  ((>= i n) fib) '())
))

(define (main args) (if (not (equal? (length args) 2)) 
  (display 
  (string-append "Usage:\n\t" (car args) " (n-th fibonacci # to calculate)\n"))
  (let ((n (car (cdr args)))) 
  (display
  (string-append "fibonacci(" n "): " 
     (number->string (fibonacci (string->number n)))
  ))))
)