Loathe as I am to engage in a programming language pissing-match, I think you will be surprised at how widely lua is embedded, perhaps even in products that you have used.

http://en.wikipedia.org/wiki/Lua_%28programming_language%29#...

Now you do! Well, I don't use it, but I work in Ann Arbor, and a guy who sits about 30 feet from me uses it in his product.

You should not evaluate the worth of something by the number of people that use it.

Pithy and sounds good, but totally discounts network effects. Programming languages are subject to network effects -- users create libraries in the language, increasing the usefulness of the language. Of course, interoperation between languages is possible to some degree, but that doesn't detract from the core statement.

It's really not hard to use C libraries from Lua, and its design for embedding / use as an off-the-shelf extension language has made interfacing easily with other languages a high priority.

There are projects that supposedly allow interoperability with Python, Perl, and several other languages (http://lua-users.org/wiki/BindingCodeToLua), though I have only used the C API thus far.

The core language is also small and simple enough that adding major language extensions, such as Erlang's concurrency model (http://concurrentlua.luaforge.net/), is feasible.

> It's really not hard to use C libraries from Lua, ...

My understanding is that it's actually very easy to use C libs from Lua.

You have to be comfortable with C, so that rules out some people.

Many useful libraries are in languages other than C.