refactor: Herstructurering

src/prolog/ast/terms/Goal.kt

@@ -0,0 +1,18 @@
+package prolog.ast.terms
+
+import prolog.Program
+import prolog.ast.logic.Provable
+import prolog.logic.Substituted
+
+/**
+ * Ask the Prolog engine.
+ *
+ * A goal is either an [Atom] or a [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 : Term, Provable {
+    abstract val functor: Functor
+
+    override fun prove(subs: Substituted): Sequence<Substituted> = Program.solve(this, subs)
+}