Which language should I use? [closed]

Answer 1

The only thing I can really comment on is this: PHP is bascially a DSL for the web, whereas the other three (Perl, Ruby, Python) are more general-purpose languages that have no specific domain, although all are definitely web-capable.

In terms of your second bullet point, I think PHP will probably be the worst choice out of your list.

Answer 2

Lisp has been mentioned, but I think Scheme (in particular plt-scheme) is in some respects as good a choice as Ruby/Python/Perl/PHP. It doesn't have as many good libraries as some of those, which is a minus, but most schemes have excellent ffi (foreign function interface), which makes it trivial to integrate external (C code) libraries. Another strength of scheme is its performance profile; You can often get near C-code type performance on number-crunching stuff.