From f98a2d5e0131f47de30c422fd69ca067453f92e0 Mon Sep 17 00:00:00 2001
From: Vitor Santos Costa <vsc@dcc.fc.up.pt>
Date: Thu, 17 Jan 2013 14:00:12 +0000
Subject: [PATCH] fix unbound throw (obs from Paualo Moura).

---
 pl/boot.yap | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/pl/boot.yap b/pl/boot.yap
index aad4dddf7..2d2f6074f 100755
--- a/pl/boot.yap
+++ b/pl/boot.yap
@@ -1194,8 +1194,12 @@ throw(_Ball) :-
 	!,
 	'$jump_env_and_store_ball'(Ball).
 throw(Ball) :-
+	( var(Ball) -> 
+	    '$do_error'(instantiation_error,throw(Ball))
+	;
 	% get current jump point
-	'$jump_env_and_store_ball'(Ball).
+	    '$jump_env_and_store_ball'(Ball)
+	).
 
 
 % just create a choice-point