Added loose operators

src/interpreter/Preprocessor.kt

@@ -64,9 +64,9 @@ open class Preprocessor {
                     Functor.of("functor/3") -> FunctorOp(args[0], args[1], args[2])
                     Functor.of("arg/3") -> Arg(args[0], args[1], args[2])
                     Functor.of("clause/2") -> ClauseOp(args[0] as Head, args[1] as Body)
-                    Functor.of("atomic/1") -> AtomicOp(args[0])
-                    Functor.of("compound/1") -> CompoundOp(args[0])
                     Functor.of("=../2") -> Univ(args[0], args[1])
+                    Functor.of("numbervars/1") -> NumberVars(args[0])
+                    Functor.of("numbervars/3") -> NumberVars(args[0], args[1] as Integer, args[2])
 
                     // Arithmetic
                     Functor.of("inf/0") -> Integer(Int.MAX_VALUE)
@@ -172,6 +172,12 @@ open class Preprocessor {
                     Functor.of("==/2") -> Equivalent(args[0], args[1])
                     Functor.of("\\==/2") -> NotEquivalent(args[0], args[1])
 
+                    // Verification
+                    Functor.of("atomic/1") -> Atomic(args[0])
+                    Functor.of("compound/1") -> Compound(args[0])
+                    Functor.of("nonvar/1") -> NonVar(args[0])
+                    Functor.of("var/1") -> Var(args[0])
+
                     Functor.of(":-/2") -> Rule(args[0] as Head, args[1] as Body)
 
                     else -> {

src/prolog/ast/terms/Functor.kt

@@ -4,6 +4,8 @@ import prolog.Substitutions
 import prolog.ast.arithmetic.Integer
 
 data class Functor(val name: Atom, val arity: Integer) : Term {
+    constructor(name: String, arity: Int) : this(Atom(name), Integer(arity))
+
     companion object {
         fun of(functor: String): Functor {
             // Split the functor string into name and arity, by splitting the last "/"

src/prolog/builtins/analysisOperators.kt

@@ -1,5 +1,6 @@
 package prolog.builtins
 
+import com.sun.tools.javac.resources.CompilerProperties.Fragments.Anonymous
 import prolog.Answers
 import prolog.Substitutions
 import prolog.ast.Database.Program
@@ -16,6 +17,8 @@ import prolog.ast.lists.List.Cons
  *
  * If Term is a [Variable] it is unified with a new term whose arguments are all different variables.
  * If Term is [atomic], Arity will be unified with the integer 0, and Name will be unified with Term.
+ *
+ * Source: [SWI-Prolog Predicate functor/3](https://www.swi-prolog.org/pldoc/doc_for?object=functor/3)
  */
 class FunctorOp(private val term: Term, private val functorName: Term, private val functorArity: Term) :
     Structure(Atom("functor"), listOf(term, functorName, functorArity)) {
@@ -154,30 +157,6 @@ class ClauseOp(private val head: Head, private val body: Body) :
     )
 }
 
-class AtomicOp(private val term: Term) : Operator(Atom("atomic"), null, term) {
-    override fun satisfy(subs: Substitutions): Answers {
-        return if (atomic(term, subs)) {
-            sequenceOf(Result.success(emptyMap()))
-        } else {
-            emptySequence()
-        }
-    }
-
-    override fun applySubstitution(subs: Substitutions): AtomicOp = AtomicOp(term.applySubstitution(subs))
-}
-
-class CompoundOp(private val term: Term) : Operator(Atom("compound"), null, term) {
-    override fun satisfy(subs: Substitutions): Answers {
-        return if (compound(term, subs)) {
-            sequenceOf(Result.success(emptyMap()))
-        } else {
-            emptySequence()
-        }
-    }
-
-    override fun applySubstitution(subs: Substitutions): CompoundOp = CompoundOp(term.applySubstitution(subs))
-}
-
 open class Univ(private val term: Term, private val list: Term) : Operator(Atom("=.."), term, list) {
     override fun satisfy(subs: Substitutions): Answers {
         return when {
@@ -246,3 +225,23 @@ open class Univ(private val term: Term, private val list: Term) : Operator(Atom(
         list.applySubstitution(subs)
     )
 }
+
+class NumberVars(private val term: Term, private val start: Integer, private val end: Term) :
+    Structure(Atom("numbervars"), listOf(term, start, end)) {
+    private var yieldEnd: Boolean = true
+
+    constructor(term: Term) : this(term, Integer(0), AnonymousVariable.create()) {
+        yieldEnd = false
+    }
+
+    override fun satisfy(subs: Substitutions): Answers = sequence {
+        val (newEnd, newSubs) = numbervars(term, start.value, subs)
+        unifyLazy(end, Integer(newEnd), subs).forEach { endResult ->
+            endResult.map { endSubs ->
+                val result = if (yieldEnd) (newSubs + endSubs) else newSubs
+                yield(Result.success(result))
+            }
+
+        }
+    }
+}

src/prolog/builtins/verificationOperators.kt

@@ -0,0 +1,57 @@
+package prolog.builtins
+
+import prolog.Answers
+import prolog.Substitutions
+import prolog.ast.terms.Atom
+import prolog.ast.terms.Operator
+import prolog.ast.terms.Term
+import prolog.logic.applySubstitution
+import prolog.logic.atomic
+import prolog.logic.compound
+import prolog.logic.nonvariable
+import prolog.logic.variable
+
+class Atomic(private val term: Term) : Operator(Atom("atomic"), null, term) {
+    override fun satisfy(subs: Substitutions): Answers {
+        if (atomic(term, subs)) {
+            return sequenceOf(Result.success(emptyMap()))
+        }
+        return emptySequence()
+    }
+
+    override fun applySubstitution(subs: Substitutions): Atomic = Atomic(applySubstitution(term, subs))
+}
+
+class Compound(private val term: Term) : Operator(Atom("compound"), null, term) {
+    override fun satisfy(subs: Substitutions): Answers {
+        if (compound(term, subs)) {
+            return sequenceOf(Result.success(emptyMap()))
+        }
+        return emptySequence()
+    }
+
+    override fun applySubstitution(subs: Substitutions): Compound = Compound(applySubstitution(term, subs))
+}
+
+class NonVar(private val term: Term) : Operator(Atom("nonvar"), null, term) {
+    override fun satisfy(subs: Substitutions): Answers {
+        if (nonvariable(term, subs)) {
+            return sequenceOf(Result.success(emptyMap()))
+        }
+
+        return emptySequence()
+    }
+
+    override fun applySubstitution(subs: Substitutions): NonVar = NonVar(applySubstitution(term, subs))
+}
+
+class Var(private val term: Term) : Operator(Atom("var"), null, term) {
+    override fun satisfy(subs: Substitutions): Answers {
+        if (variable(term, subs)) {
+            return sequenceOf(Result.success(emptyMap()))
+        }
+        return emptySequence()
+    }
+
+    override fun applySubstitution(subs: Substitutions): Var = Var(applySubstitution(term, subs))
+}

src/prolog/logic/terms.kt

@@ -1,29 +1,10 @@
 package prolog.logic
 
 import prolog.Substitutions
-import prolog.ast.terms.Atom
 import prolog.ast.terms.Structure
 import prolog.ast.terms.Term
 import prolog.ast.terms.Variable
 
-/**
- * True when Term is a term with functor Name/Arity. If Term is a variable it is unified with a new term whose
- * arguments are all different variables (such a term is called a skeleton). If Term is atomic, Arity will be unified
- * with the integer 0, and Name will be unified with Term. Raises instantiation_error() if Term is unbound and
- * Name/Arity is insufficiently instantiated.
- *
- * SWI-Prolog also supports terms with arity 0, as in a() (see
- * [section 5](https://www.swi-prolog.org/pldoc/man?section=extensions)). Such terms must be processed using functor/4
- * or compound_name_arity/3. The predicate functor/3 and =../2 raise a domain_error when faced with these terms.
- * Without this precaution a round trip of a term with arity 0 over functor/3 would create an atom.
- *
- * Source: [SWI-Prolog Predicate functor/3](https://www.swi-prolog.org/pldoc/doc_for?object=functor/3)
- */
-fun functor(term: Term, name: Atom, arity: Int): Boolean {
-    // TODO Implement
-    return true
-}
-
 /**
  * Unify the free variables in Term with a term $VAR(N), where N is the number of the variable.
  * Counting starts at Start.

tests/prolog/logic/TermAnalysisConstructionTest.kt

@@ -1,10 +1,13 @@
 package prolog.logic
 
+import org.junit.jupiter.api.Assertions.assertEquals
 import org.junit.jupiter.api.Assertions.assertFalse
 import org.junit.jupiter.api.Assertions.assertTrue
 import org.junit.jupiter.api.Test
 import prolog.ast.terms.Atom
+import prolog.ast.terms.Functor
 import prolog.ast.terms.Structure
+import prolog.ast.arithmetic.Integer
 
 /**
  * Based on [Predicates for analyzing/constructing terms](https://github.com/dtonhofer/prolog_notes/blob/master/swipl_notes/about_term_analysis_and_construction/term_analysis_construction.png)
@@ -19,7 +22,7 @@ class TermAnalysisConstructionTest {
         assertTrue(atomic(atom))
         assertFalse(compound(atom))
 
-        assertTrue(functor(atom, Atom("foo"), 0))
+        assertEquals(Functor("foo", 0), atom.functor)
     }
 
     @Test
@@ -37,6 +40,6 @@ class TermAnalysisConstructionTest {
         assertFalse(atomic(structure))
         assertTrue(compound(structure))
 
-        assertTrue(functor(structure, Atom("foo"), 1))
+        assertEquals(Functor("foo", 1), structure.functor)
     }
 }