Checkpoint

src/interpreter/Preprocessor.kt

@@ -59,6 +59,7 @@ open class Preprocessor {
             Structure(Atom("!"), emptyList()) -> Cut()
             Atom("inf") -> Integer(Int.MAX_VALUE)
             Atom("nl") -> Nl
+            Variable("_") -> AnonymousVariable.create()
             is Structure -> {
                 // Preprocess the arguments first to recognize builtins
                 val args = term.arguments.map { preprocess(it, nested = true) }
@@ -86,6 +87,10 @@ open class Preprocessor {
                         Not(args[0] as Goal)
                     }
 
+                    term.functor == "==/2" -> {
+                        Equivalent(args[0], args[1])
+                    }
+
                     term.functor == "=\\=/2" && args.all { it is Expression } -> {
                         EvaluatesToDifferent(args[0] as Expression, args[1] as Expression)
                     }
@@ -133,7 +138,10 @@ open class Preprocessor {
                     term.functor == "read/1" -> Read(args[0])
                     term.functor == "initialization/1" -> Initialization(args[0] as Goal)
 
-                    else -> term
+                    else -> {
+                        term.arguments = args
+                        term
+                    }
                 }
             }