I think David wrote: > Hello, > > > Q1. > I am kind of confused because in pg 42, it is mentioned that a symbol > cannot have ? as the first character. However in page 47, it is pointed > that most jess variables are written as symbols that begin with a > question mark.
The book uses "lazy language" to describe the Jess grammar; there could be an EBNF grammar, I suppose, although it would be quite messy. But the existing text is not terribly precise. It could say, to be painfully exact, that 1) A symbol cannot contain a '?'. 2) A variable name is a symbol. 3) You refer to a variable in Jess code by writing its name preceded by a question mark. > I tried to do (bind x 100), it did not work. Right. Here x is a symbol. ?x is a variable named 'x'. > > Q2 . > Can I clarify that ALL variables in Jess MUST start with a question mark > ? Regular variables will always be written beginning with a '?'. Multifields are written with "$?". Therefore, it's not correct to say that ALL variables MUST start with a question mark. But they must start with one or the other. --------------------------------------------------------- Ernest Friedman-Hill Science and Engineering PSEs Phone: (925) 294-2154 Sandia National Labs FAX: (925) 294-2234 PO Box 969, MS 9012 [EMAIL PROTECTED] Livermore, CA 94550 http://herzberg.ca.sandia.gov -------------------------------------------------------------------- To unsubscribe, send the words 'unsubscribe jess-users [EMAIL PROTECTED]' in the BODY of a message to [EMAIL PROTECTED], NOT to the list (use your own address!) List problems? Notify [EMAIL PROTECTED] --------------------------------------------------------------------
