;; #!/usr/bin/env gosh

;; Gauche

(import (scheme base)
        (scheme write)
        (srfi 27)
        (gauche base)
        (record-vector))

(define N-Vehicles 100000)

(define (rndx) (* (random-real) 1000.))
(define (rndw) (+ 900 (random-integer 200)))

(define-syntax dotimes
  (syntax-rules ()
    ((_ n f ...)
     (do ((i 0 (+ 1 i)))
         ((= i n))
       f ...))))

(define (main args)
  (let* ((step 0.1) ;; sec
         (friction 0.01)
         (v (make-rv :x 0.0 :speed 0.0 :accel 0.1 :mass 1000))
         (vecs (do ((i 0 (+ 1 i))
                    (vs (make-vector N-Vehicles)))
                   ((= i (vector-length vs)) vs)
                 (vector-set! vs i (rv-clone v :mass (rndw))))))
    (dotimes 1000
      (vector-for-each
       (lambda (vh)
         (rv-set! vh :x (+ (rv-ref vh :x) (* (rv-ref vh :speed) step)))
         (rv-set! vh :speed (+ (rv-ref vh :speed) (* (rv-ref vh :accel) step))))
       vecs))

      (format  "[0].x = ~a" (rv-ref (vector-ref vecs 0) :x))
    ))

;; from ..
;; gosh -A .
;; > (load "examples/recalc-gauche.scm")
;; > ,time (main)