#lang racket
(require (planet wcy/mpost-wrapper))
(provide main)
(define (main)
  (define (compute_curve f xmin xmax xinc)
    (apply op.. (for/list ((x (in-range xmin xmax xinc)))
                          (point x (f x)))))
  (define (f x)
    (op+ 1 (op** x 2)))
  (define (g x)
    (op- 2 (op** (op- x 1) 2)))
  (let* ((p (scale '1cm (compute_curve f -1 1.5 0.1)))
         (q (scale '1cm (compute_curve g -0.5 2 0.1))))
    (fill (buildcycle p (op-reverse q)) #:withcolor (op+ 'red 'green))
    (draw p #:withpen (scale '1bp 'pencircle))
    (draw q #:withpen (scale '1bp 'pencircle))
    (draw (op-- (point '-1cm 0)  (point '2cm 0)))
    (draw (op-- (point 0 (op* (g -0.5) '1cm))
                (point 0 (op* (f  1.5) '1cm))))
    ))