Subject: tell/1 , append/1 , open/4 ??????

From: jfd <[email-masked]>
Date: Wed, 22 Dec 1999 11:27:56 +0500

Hi,
in a course for foundation of programming, we have written a
demonstration editor...
So that the student can show their demonstrations, i have written a
couple of clauses which copy in a file (trace.dem') the screen session : 
%predicats de service

dw(X)
		:-
		tell('trace.dem'),
		write(X),
		tell(user),
		write(X).

dnl
		:-
		tell('trace.dem'),
		nl,
		tell(user),
		nl.

'DR'(X) 
		:-
		read(X),
		tell('trace.dem') , 
		write(X) , nl , tell(user) , nl.

This work well with simple Prolog (OPEN on macOS) and not
with SWI 3.2.8
what wrong in this picture ?
help , help

jfd