From: Markus Triska <triska@metalevel.at>
Date: Wed, 3 Feb 2021 22:49:28 +0000 (+0100)
Subject: add meta_predicate declaration for must_succeed/1
X-Git-Tag: v0.9.0~150^2~66^2~3^2
X-Git-Url: https://git.sagredo.dev/?a=commitdiff_plain;h=b96ff781bc806ff37b4abe9e3b7d986728473b2a;p=scryer-prolog.git

add meta_predicate declaration for must_succeed/1
---

diff --git a/src/lib/clpz.pl b/src/lib/clpz.pl
index e72a33c1..b7fa0ea7 100644
--- a/src/lib/clpz.pl
+++ b/src/lib/clpz.pl
@@ -5884,10 +5884,12 @@ difference_arcs([V|Vs], FL0) -->
 
 writeln(T) :- write(T), nl.
 
+:- meta_predicate must_succeed(0).
+
 must_succeed(G) :-
-    (G -> true
-     ;write(failed-G), halt
-    ).
+        (   G -> true
+        ;   throw(failed-G)
+        ).
 
 enumerate([], _) --> [].
 enumerate([N|Ns], V) -->