Choosing a new language

[George Neuner]

On Fri, 28 Dec 2007 12:54:57 -0800, John Nagle <nagle at animats.com>
wrote:

>    Actually, the ability to "fix a running program" [in Lisp] isn't
>that useful in real life.  It's more cool than useful.  Editing a 
>program from a break was more important back when computers were slower
>and just rerunning from the beginning was expensive.

Speak for yourself.

The ability to patch a running program is very useful for certain
types of embedded applications.  Not every program having high
availability requirements can be restarted quickly, or can be
implemented reasonably using multiple servers or processes to allow
rolling restarts.

I worked with real time programs that required external machinery to
operate and several minutes to reinitialize and recover from a cold
restart.  Debugging non-trivial code changes could take hours or days
without the ability to hot patch and continue.  I know not everyone
works in RT, but I can't possibly be alone in developing applications
that are hard to restart effectively.

That all said, online compilation such as in Lisp is only one of
several ways of replacing running code.  Whether it is the best way is
open for debate.

George
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