I wonder how large (or small) that restricted subset is and how easily it is 'violated', turning off the optimization although it would have been possible (For

I wonder how large (or small) that restricted subset is and how easily it is 'violated', turning off the optimization although it would have been possible (For example, the global hash could be referred to via a local variable which might carry the result of a function call). Do you have any insights on that? Until then, using a 'dirty flag' on the `chr` definition that turns off the optimization at run time as mentioned elsewhere in this thread, seems to be the appropriate approach for me.