#define N 80 * 25

datatype color =
  | Black 
  | Blue 
  | Green 
  | Cyan 
  | Red 
  | Magenta 
  | Brown 
  | LightGray 
  | DarkGray 
  | LightBlue 
  | LightGreen 
  | LightCyan 
  | LightRed 
  | Pink 
  | Yellow 
  | White 


typedef screenChar = @{ ascii_character = char, color_code = uint8}

vtypedef tptr (a: t@ype, l:addr) = (a @ l | ptr l)
vtypedef writer = [l: addr] [n:nat | n < N] @{ column_position = size_t n, color_code = uint8 , buffer = tptr(@[screenChar][N],l)}

fun print_char(c : char) : void