Tim Holy introduced me to the wonders of @code_warntype in this
discussion https://groups.google.com/forum/#!topic/julia-users/sq5gj-3TdQU.
I've since been using it to track down other instabilities in my code
since it turns out that I'm very good at writing poor julia code. Are
there any plans to incorporate automatic warnings about type unstable
functions when they are compiled? Maybe even via a startup flag like
`-Wunstable`? I would prefer that its on by default. This would go a long
way towards helping me write much better code and probably help new users
get more of the performance they were expecting.
