From: Markus Triska <triska@metalevel.at>
Date: Tue, 23 Jan 2024 20:43:34 +0000 (+0100)
Subject: improve error context
X-Git-Tag: v0.9.4~22^2
X-Git-Url: https://git.sagredo.dev/?a=commitdiff_plain;h=a6ccf95076fbf0441ccbe894c399310e2f9139ad;p=scryer-prolog.git

improve error context

Source: https://github.com/mthom/scryer-prolog/issues/2304#issuecomment-1906434756
---

diff --git a/src/lib/dcgs.pl b/src/lib/dcgs.pl
index 0fa9109c..4ee763f0 100644
--- a/src/lib/dcgs.pl
+++ b/src/lib/dcgs.pl
@@ -174,10 +174,10 @@ dcg_constr(phrase(_)). % 7.14.9
 dcg_constr(phrase(_,_)). % extension of 7.14.9
 dcg_constr(phrase(_,_,_)). % extension of 7.14.9
 dcg_constr(!). % 7.14.10
-dcg_constr(\+ _) :- % 7.14.11 - not (existence implementation dep.)
-    throw(error(representation_error(dcg_body), phrase/3)).
-dcg_constr((_->_)) :- % 7.14.12 - if-then (existence implementation dep.)
-    throw(error(representation_error(dcg_body), phrase/3)).
+dcg_constr(\+ G_0) :- % 7.14.11 - not (existence implementation def.)
+    throw(error(representation_error(dcg_body), [culprit- (\+ G_0)])).
+dcg_constr((If->Then)) :- % 7.14.12 - if-then (existence implementation def.)
+    throw(error(representation_error(dcg_body), [culprit- (If->Then)])).
 
 % The principal functor of the first argument indicates
 % the construct to be expanded.