[jrochkind1]

awesome, thanks. Looks like that backport may be only for ruby 2.0 (not 1.9), and is a compiled C extension.

It won't take many lines of pure ruby code to do it for ruby 1.9 too, although presumably not performing quite as well as a C version.

At any rate, this is definitely something I and people I know need to do all the time, although apparently most ruby devs never need to do it; but I'm glad it's finally made it into stdlib.