T Colour = BVec3

V black = Colour(0, 0, 0)
V white = Colour(255, 255, 255)

T Bitmap
   Int width, height
   Colour background
   [[Colour]] map

   F (width = 40, height = 40, background = white)
      assert(width > 0 & height > 0)
      .width = width
      .height = height
      .background = background
      .map = (0 .< height).map(h -> (0 .< @width).map(w -> @@background))

   F fillrect(x, y, width, height, colour = black)
      assert(x >= 0 & y >= 0 & width > 0 & height > 0)
      L(h) 0 .< height
         L(w) 0 .< width
            .map[y + h][x + w] = colour

   F set(x, y, colour = black)
      .map[y][x] = colour

   F get(x, y)
      R .map[y][x]

   F writeppmp3()
      V magic = "P3\n"
      V comment = "# generated from Bitmap.writeppmp3\n"
      V s = magic‘’comment‘’("#. #.\n#.\n".format(.width, .height, 255))
      L(h) (.height - 1 .< -1).step(-1)
         L(w) 0 .< .width
            V (r, g, b) = .get(w, h)
            s ‘’= ‘   #3 #3 #3’.format(r, g, b)
         s ‘’= "\n"
      R s

   F writeppmp6()
      V magic = "P6\n"
      V comment = "# generated from Bitmap.writeppmp6\n"
      [Byte] b
      b [+]= magic.encode()
      b [+]= comment.encode()
      b [+]= ("#. #.\n#.\n".format(.width, .height, 255)).encode()
      L(h) (.height - 1 .< -1).step(-1)
         L(w) 0 .< .width
            V (r, g, bl) = .get(w, h)
            b [+]= [r, g, bl]
      R b

V bitmap = Bitmap(4, 4, black)
bitmap.fillrect(1, 0, 1, 2, white)
bitmap.set(3, 3, Colour(127, 0, 63))
print(bitmap.writeppmp3())

File(‘tmp.ppm’, WRITE).write_bytes(bitmap.writeppmp6())