ex-3.77.scm

(require "./stream-lib")

(define (integral delayed-integrand initial-value dt)
  (cons-stream initial-value
               (let ((integrand (force delayed-integrand)))
                 (if (stream-null? integrand)
                  the-empty-stream
                  (integral (delay (stream-cdr integrand))
                            (+ (* dt (stream-car integrand))
                               initial-value)
                            dt)))))

(define (solve f y0 dt)
  (define y (integral (delay dy) y0 dt))
  (define dy (stream-map f y))
  y)

(define (main args)
  (print (stream-ref (solve (lambda (y) y) 1 0.001) 1000))
  )