Apologies for the wording of my comment. What I mean is that you don't have to worry about libraries for languages a lot if you can use the power of your OS ecosystem (especially, *nix one) in your application (considering performance and other limitations).

If it was just as easy, why wasn't it done?

Doing system requires forking your entire interpreter/VM. That's a huge performance penalty.

There is performance penalty, but come on:

Under Linux, fork() is implemented using copy-on-write pages, so the only penalty that it incurs is the time and memory required to duplicate the parent's page tables, and to create a unique task structure for the child.

(from fork(1) man pages)

> " time and memory required to duplicate the parent's page tables "

Performance penalty is fairly significant ( unless it's done up front, i.e. to setup a pool of processes, like Apache's prefork mpm ). So doing a fork() per each request is actually a really bad idea (as is creating a new thread, but that's a whole other rant I have reserved) -- I'd say it's an anti-pattern (in Java world it's the "one thread per connection" Enterprise(TM)(R) idiocy lot of servlet containers do/users to do disregarding ThreadPools and NIO).

Memory penalty really depends on your language and its VM (and it's assuming no memory leaks). I haven't looked at arc + mzscheme, but it's actually a big issue for me at work with Perl right now at my present work (too much functionality was implement as cronjobs invoking Perl scripts which do system() after system() -- vs. doing it as daemons doing xs calls into C libraries).

I'll grant mzscheme and arc are likely lighter weight than Perl and its JIT, but unless you're doing pure C it's only a matter of degree.

Well, as you can see, HN serves a lot of traffic and has a system() call :-)

Of course, everything is compromise between performance, ease of use, features etc. I'm not arguing with this.

HN isn't a commercial site and actively tries to restrict traffic. The advantage of having already made something people want is that you can make non-commercialized sites and limit the growth to the level you find comfortable :-)