Subject: Re: the meaning of ";"

From: Fred Dushin <[email-masked]>
Date: Fri, 21 May 1999 09:31:55 -0400 (EDT)

On Thu, 20 May 1999, Amir Wolf wrote:

> What is the meaning  of  " ; " in prolog 

'Or', last time I used it.  

> and what is the meaning of  " () " ?

Do you mean '()' or '(t_1, ..., t_n)'?

In general, () is used by the prolog parser to group terms
using infix operators (',', ';', etc.)  Jan may have
a better answer to this.

An interesting observation:  ',' is a *binary* functor,
despite its occurrence in terms like '(t_1, ..., t_n)'.
Internally, such a term has the following represenatation:

	','( t_1, ','( t_1, ..., ','( t_{n-1}, t_n )...))

Maybe Jab can clarify for other cases, like ';' or user-defined
operators.

-Fred

--
Fred Dushin                      mailto:[email-masked]
PGP public key available at      http://blackcat.cat.syr.edu/~fadushin/pgp