+digit = do c <- anyChar
+ if c >= '0' && c <= '9' then
+ return c
+ else
+ fail ""
+
+
+hexDigit :: Parser Char
+hexDigit = do c <- anyChar
+ if (c >= '0' && c <= '9') ||
+ (c >= 'a' && c <= 'f') ||
+ (c >= 'A' && c <= 'F') then
+ return c
+ else
+ fail ""