[repsilat]

I think this is still a library problem, not a language problem. "Compiling" a string at runtime for `sprintf` isn't any more difficult than doing it at compile-time, and plenty of regex libraries do very similar things.

Compiling of printf strings isn't done, though, because nobody cares about string performance unless they're writing UNIX command-line utils. If you're writing C you're probably only dealing with strings for (infrequent) IO, spending the vast majority of your time crunching away on pointers and integer types (floats in niche cases). In the end, you're probably only printing something out because someone needs to read it, and how fast can humans read, anyway?

This goes just as much for the printing of floating point numbers. (http://www.serpentine.com/blog/2011/06/29/here-be-dragons-ad...)