It works, basic but works, need to move out logic to places, like ASTNode array shouldn't be on the lexer or future logic for fractions and error handling in the evaluator. Just the things at the top of my head

include/evaluator.h

@@ -0,0 +1,9 @@
+#ifndef EVALUATOR_H
+#define EVALUATOR_H
+
+#include "lexer.h"
+#include <stdint.h>
+
+uint64_t evaluate(ASTNode *tree);
+
+#endif // !EVALUATOR_H