(
  (globals . (
    (mac . [(define mac (litmac litfn () ((name . params) . body)
  `(define ,name (litmac litfn () ,params ,@body))))])
    (def . [(mac (def (name . params) . body)
  `(define ,name (fn ,params ,@body)))])
    (do . [(mac (do . body) `((fn () ,@body)))])
    (list . [(def (list . args) args)])
    (len . [(def (len l)
  (if (no l)
    0
    (+ 1 (len (cdr l)))))])
    (map1 . [(def (map1 f xs)
  (if (no xs)
    ()
    (cons (f (car xs))
          (map1 f (cdr xs)))))])
    (let . [(mac (let var val . body)
  `((fn (,var) ,@body) ,val))])
    (when . [(mac (when cond . body)
  `(if ,cond (do ,@body) ()))])
    (++ . [(mac (++ var) `(set ,var (+ ,var 1)))])
    (+= . [(mac (+= var inc)
  `(set ,var (+ ,var ,inc)))])
    (for . [(mac (for var init test update . body)
  `(let ,var ,init
     (while ,test
       ,@body
       ,update)))])
    (hline1 . [(def (hline1 screen y x xmax color)
  (while (< x xmax)
    (pixel screen x y color)
    (++ x)))])
    (vline1 . [(def (vline1 screen x y ymax color)
  (while (< y ymax)
    (pixel screen x y color)
    (++ y)))])
    (hline . [(def (hline screen y color)
  (hline1 screen y 0 (width screen) color))])
    (vline . [(def (vline screen x color)
  (vline1 screen x 0 (height screen) color))])
    (line . [(def (line screen x0 y0 x1 y1 color)
  (let (x y) `(,x0 ,y0)
  (let dx (abs (- x1 x0))
  (let dy (- 0 (abs (- y1 y0)))
  (let sx (sgn (- x1 x0))
  (let sy (sgn (- y1 y0))
  (let err (+ dx dy)
  (while (not (and (= x x1)
                   (= y y1)))
    (pixel screen x y color)
    (let e2 (* err 2)
    (when (>= e2 dy)
      (+= x sx))
    (when (<= e2 dx)
      (+= y sy))
    (+= err
        (+ (if (>= e2 dy)
             dy
             0)
           (if (<= e2 dx)
             dx
             0))))))))))))])
    (read_line . [(def (read_line keyboard)
  (let str (stream)
  (let c (key keyboard)
    (while (not (or (= c 0) (= c 10)))
      (write str c)
      (set c (key keyboard))))
  str))])
    (wait . [(def (wait keyboard)
  (while (= 0 (key keyboard))))])
    (sq . [(def (sq n) (* n n))])
    (cube . [(def (cube n) (* (* n n) n))])
    (fill_rect . [(def (fill_rect screen x1 y1 x2 y2 color)
  (for y y1 (< y y2) (++ y)
    (hline1 screen y x1 x2 color)))])
    (chessboard_row . [(def (chessboard_row screen px y x xmax)
  (while (< x xmax)
    (fill_rect screen
               x        y
               (+ x px) (+ y px) 15)
    (+= x (* px 2))))])
    (chessboard . [(def (chessboard screen px)
  (clear screen)
  (let xmax (width screen)
  (let ymax (height screen)
  (for y 0 (< y ymax) (+= y px)
    (chessboard_row screen px y 0 xmax)
    (+= y px)
    (chessboard_row screen px y px xmax)))))])
    (circle . [(def (circle screen cx cy r clr)
  (let x (- 0 r)
  (let y 0
  (let err (- 2 (* 2 r))
  (let continue 1
  (while continue
    (pixel screen (- cx x) (+ cy y) clr)
    (pixel screen (- cx y) (- cy x) clr)
    (pixel screen (+ cx x) (- cy y) clr)
    (pixel screen (+ cx y) (+ cy x) clr)
    (set r err)
    (when (<= r y)
      (++ y)
      (+= err
          (+ 1 (* 2 y))))
    (when (or (> r x) (> err y))
      (++ x)
      (+= err
          (+ 1 (* 2 x))))
    (set continue (< x 0))))))))])
    (ring . [(def (ring screen cx cy r0 w clr)
  (for r r0 (< r (+ r0 w)) (++ r)
    (circle screen cx cy r clr)))])
    (circle_rainbow . [(def (circle_rainbow scr cx cy r w)
  (ring scr cx cy r w 37)
  (+= r w)
  (ring scr cx cy r w 33)
  (+= r w)
  (ring scr cx cy r w 55)
  (+= r w)
  (ring scr cx cy r w 52)
  (+= r w)
  (ring scr cx cy r w 47)
  (+= r w)
  (ring scr cx cy r w 45)
  (+= r w)
  (ring scr cx cy r w 44)
  (+= r w)
  (ring scr cx cy r w 42)
  (+= r w)
  (ring scr cx cy r w 41)
  (+= r w)
  (ring scr cx cy r w 40))])
    (bowboard . [(def (bowboard screen r)
  (let xmax (width screen)
  (let ymax (height screen)
  (let side (* 2 r)
  (for y r (< y ymax) (+= y side)
    (for x r (< x xmax) (+= x side)
      (circle_rainbow screen x y (- r 100) 10)))))))])
    (task . [(def (task screen keyboard)
  (let xmax (width screen)
  (let ymax (height screen)
  (for y 0 (< y ymax) (+= y 4)
    #(wait keyboard)
    (for x 0 (< x xmax) (+= x 1)
      (pixel screen x y
             # color
             (+ 16 (+ (/ x 4) (cube (/ y 4))))))))))])
    (main . [(def (main screen keyboard)
  (task screen keyboard))])
  ))
  (sandbox . (task screen keyboard))
)