very basic parser of let statements

src/ast/ast.cpp

@@ -0,0 +1,9 @@
+#include "ast.hpp"
+
+namespace ast {
+    std::string program ::token_literal() const {
+        if (statements.size() > 0)
+            return statements[0]->token_literal();
+        return "";
+    }
+} // namespace ast