Throw errors when trying to evaluate goals that cannot be evaluated

1 files changed, 5 insertions, 0 deletions

diff --git a/eval.c b/eval.c
index 09bb009..e57f28f 100644
--- a/eval.c
+++ b/eval.c
@@ -28,6 +28,11 @@ evalquery(Term *query)
 		if(flagdebug)
 			print("Working goal: %S:%S\n", module->name, prettyprint(goal, 0, 0, 0, nil));
 
+		if(goal->tag == VariableTerm)
+			goal = instantiationerror();
+		if(goal->tag != AtomTerm && goal->tag != CompoundTerm)
+			goal = typeerror(L"callable", goal);
+
 		Binding *bindings = nil;
 		Clause *clause = nil;