Python/django I'm not so sure, but ruby/rails illustrates the point well. Ruby rose and fell with rails. It existed in relative obscurity for a decade before ra

Python/django I'm not so sure, but ruby/rails illustrates the point well. Ruby rose and fell with rails. It existed in relative obscurity for a decade before rails came along and showed that world what you could do with it. Despite it's merits (I like ruby) without this killer app most programmers would probably have never heard of it. Functional languages don't really have that killer app, the only things I can think of that's close is emacs.