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Prevent assertion of clauses for (-->)/2 when DCGs are enabled.

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This addresses #1508.
This commit is contained in:
Markus Triska
2024-01-05 18:50:08 +01:00
parent d51defed06
commit f2b63d1689
1 changed files with 9 additions and 1 deletions
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10
src/lib/dcgs.pl
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@@ -14,7 +14,8 @@ to learn more about them.
phrase/3, phrase/3,
seq//1, seq//1,
seqq//1, seqq//1,
... //0 ... //0,
(-->)/2
]). ]).
:- use_module(library(error)). :- use_module(library(error)).
@@ -220,3 +221,10 @@ user:goal_expansion(phrase(GRBody, S, S0), GRBody2) :-
). ).
user:goal_expansion(phrase(GRBody, S), phrase(GRBody, S, [])). user:goal_expansion(phrase(GRBody, S), phrase(GRBody, S, [])).
% (-->)/2 behaves as if it didn't exist. We export (and define) it
% only so that clauses for (-->)/2 cannot be asserted when
% library(dcgs) is loaded.
(_-->_) :- throw(error(existence_error(procedure,(-->)/2),(-->)/2)).