;; #!/usr/bin/env gsi-script

;; Gambit & CHICKEN version

(import (scheme base)
        (scheme write)
        (record-vector))

(define N-Vehicles 100000)

(define (rndx) (* (random:exp) 1000.))
(define (rndw) (+ 900 (random 200)))

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

(define (main)
  (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 #t "[0].x = ~a" (rv-ref (vector-ref vecs 0) #:x))
    ))

;; from ..
;; guile -L . --r7rs
;; > (load "examples/recalc-guile.scm")
;; > ,time (main)