Single clause queries

src/prolog/components/terms/Goal.kt

@@ -0,0 +1,16 @@
+package prolog.components.terms
+
+import prolog.components.Program
+
+/**
+ * Question stated to the Prolog engine.
+ *
+ * A goal is either an [atom][prolog.components.terms.Atom] or a [compound term][prolog.components.terms.CompoundTerm].
+ * A goal either [succeeds][prolog.builtins.True], in which case the variables in the compound terms have a binding,
+ * or it fails if Prolog fails to prove it.
+ */
+abstract class Goal : Head() {
+    fun prove(): Boolean {
+        return Program.query(this)
+    }
+}