void (*unget_char) (char c, void *data));
lisp_object_t* lisp_read (lisp_stream_t *in);
-lisp_object_t* lisp_read_from_file(const char* filename);
+lisp_object_t* lisp_read_from_file(const std::string& filename);
void lisp_free (lisp_object_t *obj);
lisp_object_t* lisp_read_from_string (const char *buf);