But the solution does need support from IDEs and parsers. STR."\{STR."\{a}"}" is a valid expression, now, that uses a variable, and looks nothing like any previ

But the solution does need support from IDEs and parsers. STR."\{STR."\{a}"}" is a valid expression, now, that uses a variable, and looks nothing like any previously valid expression. Given that it is an entirely new kind of expression, it's also unclear why they would choose \{ over { or need the dot. Is there some reason that they couldn't have chosen STR"{a}"?