Checkpoint

src/prolog/builtins/verification.kt

@@ -1,41 +0,0 @@
-package prolog.builtins
-
-import prolog.ast.terms.CompoundTerm
-import prolog.ast.terms.Term
-import prolog.ast.terms.Variable
-
-/**
- * True if [Term] is bound (i.e., not a variable) and is not compound.
- * Thus, atomic acts as if defined by:
- *
- * atomic(Term) :-
- *         nonvar(Term),
- *         \+ compound(Term).
- */
-fun atomic(term: Term): Boolean = nonvariable(term) && !compound(term)
-
-/**
- * True if [Term] is bound to a compound term.
- * See also functor/3 =../2, compound_name_arity/3 and compound_name_arguments/3.
- */
-fun compound(term: Term): Boolean {
-    val isCompound = term is CompoundTerm
-    val isVariableCompound = term is Variable && term.alias().isPresent && compound(term.alias().get())
-    return isCompound || isVariableCompound
-}
-
-/**
- * True if [Term] currently is not a free variable.
- */
-fun nonvariable(term: Term): Boolean = !variable(term)
-
-/**
- * True if [Term] currently is a free variable.
- */
-fun variable(term: Term): Boolean {
-    if (term is Variable) {
-        return term.alias().isEmpty || term.alias().get() === term || variable(term.alias().get())
-    }
-
-    return false;
-}