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From: Mild Shock <janburse@fastmail.fm>
Newsgroups: comp.lang.prolog
Subject: DCG restrictions on the left-hand side [Novacore]
Date: Tue, 30 Jul 2024 20:39:58 +0200
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Guess how many newer Prolog systems allow this here:

?- [user].
p;q --> r.
    true.

On the other hand SWI-Prolog disallows it:

?- [user].
p;q --> r.

ERROR: user://1:29:
ERROR:    No permission to define dcg_nonterminal `p;q'