User blog comment:Hyp cos/R function II/@comment-5529393-20150406080531/@comment-5529393-20150406090449

Thanks. If I read you correctly, if the whole string is a brace, then both A_1 and A_2 get set to the whole string, is that correct?

Also, it looks like that when scanning, we skip over separators. But what about something like ? That seems to be valid according to the rules, but there is nothing inside the outer brace except for a separator, so there is nothing to scan. Perhaps this should be disallowed as well?