refactor: Herstructurering

src/prolog/components/expressions/Clause.kt

@@ -1,43 +0,0 @@
-package prolog.components.expressions
-
-import prolog.Substituted
-import prolog.builtins.True
-import prolog.builtins.equivalent
-import prolog.components.Resolvent
-import prolog.components.terms.*
-import prolog.unifyLazy
-
-/**
- * ‘Sentence’ of a Prolog program.
- *
- * A clause consists of a [Head] and body separated by the [neck][prolog.terms.Neck] operator, or it is a [Fact].
- *
- * @see [prolog.components.terms.Variable]
- * @see [Predicate]
- */
-abstract class Clause(private val head: Head, private val body: Body) : Resolvent {
-    val functor: Functor = head.functor
-
-    override fun solve(goal: Goal, subs: Substituted): Sequence<Substituted> = sequence {
-        // If the clause is a rule, unify the goal with the head and then try to prove the body.
-        // Only if the body can be proven, the substitutions should be returned.
-        // Do this in a lazy way.
-        unifyLazy(goal, head, subs).forEach { newHeadSubs ->
-            // If the body can be proven, yield the (combined) substitutions
-            body.prove(subs + newHeadSubs).forEach { newBodySubs ->
-                yield(newHeadSubs + newBodySubs)
-                // Unbind the newly bound variables, so they can be reused.
-                newBodySubs.keys.forEach { it.unbind() }
-            }
-            // Unbind the newly bound variables, so they can be reused.
-            newHeadSubs.keys.forEach { it.unbind() }
-        }
-    }
-
-    override fun toString(): String {
-        return when {
-            body == True() -> head.toString()
-            else           -> "$head :- $body"
-        }
-    }
-}