refactor: remove unused code

Author: kelvin-olaiya

src/main/scala/io/github/kelvindev15/prolog/core/Struct.scala

@@ -20,13 +20,7 @@ object Struct:
   private def isFunctorWellFormed(functor: String): Boolean = functor.matches(Syntax.AtomRegex.regex)
   def quoteIfFunctorIsMalformed(functor: String): String =
     if (isFunctorWellFormed(functor)) functor else s"'$functor'"
-  def apply(functor: Atom, args: Term*): Struct = StructImpl(functor, args*)
-
-  object Functor:
-    def unapply(struct: Struct): Option[Atom] = Option(struct.functor)
-    
-  object Args:
-    def unapply(struct: Struct): Option[Iterable[Term]] = Option(struct.arguments)  
+  def apply(functor: Atom, args: Term*): Struct = StructImpl(functor, args*) 
 
   private case class StructImpl(functor: Atom, arguments: Term*) extends Struct:
     override val arity: Int = arguments.size

src/main/scala/io/github/kelvindev15/prolog/core/Theory/Theory.scala

@@ -18,13 +18,3 @@ object Theory:
     override def contains(clause: Clause): Boolean = contains(clause)
     override def length: Int = clauses.length
     override def iterator: Iterator[Clause] = clauses.iterator
-
-  class MutableTheory(var theory: Theory = Theory()) extends Theory:
-    override def add(clause: Clause): Theory = { theory = theory.add(clause) ; theory }
-    override def remove(clause: Clause): Theory = { theory = theory.remove(clause) ; theory }
-    override def contains(clause: Clause): Boolean = theory.contains(clause)
-    override def clauses: Seq[Clause] = theory.clauses
-    override def length: Int = theory.length
-    override def iterator: Iterator[Clause] = theory.iterator
-
-    override def apply(i: Int): Clause = theory(i)