From dazy@cnam.fr  Wed Dec 22 11:26:52 1999
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Date: Wed, 22 Dec 1999 11:27:56 +0500
From: jfd <dazy@cnam.fr>
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Organization: cnam
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To: prolog@swi.psy.uva.nl
Subject: tell/1 , append/1 , open/4  ??????
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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

