use Syntastic

I'm not sure if I'll stick with this or not, but its default mode of
operation seems to be about the right amount of in-your-face, at least
for the stuff I've tried it on today:  Write the buffer with a syntax
error, and you'll get strong visual indicators of the error along with
the specifics.

Useful for shortcircuiting that part of the cycle where you run the code
before realizing you're missing a paren or whatever.