cleanup and implementation of builtin functions

src/builtin-functions.h

@@ -0,0 +1,34 @@
+/*
+ * This code is part of the programming language flup
+ * flup comes with ABSOLUTELY NO WARRANTY and is licensed under AGPL-3.0 or later.
+ *    Copyright (C) 2024  VegOwOtenks
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+#ifndef FLUP_BUILTINFUNCTION_H
+#define FLUP_BUILTINFUNCTION_H
+
+#include "callframe.h"
+#include "tokenizer.h"
+
+
+int BuiltinFunction_Minus(CallFrame* top_frame);
+int BuiltinFunction_Plus(CallFrame* top_frame);
+int BuiltinFunction_Equality(CallFrame* top_frame);
+int BuiltinFunction_PrintLine(CallFrame* top_frame);
+int BuiltinFunction_Duplicate(CallFrame* top_frame);
+
+
+#endif