[JoshTriplett]

If you're reading a pile of string processing code, seeing

    s.rstrip()

helps make code self-documenting, compared to

    s:gsub("%s*$", "")

I don't want to argue for a massive standard library (for instance, I don't think Python should have shipped modules for dbm, bdb, sqlite, or XML-RPC), but simple string processing seems like a good thing to standardize.

[brandonbloom]

String processing is never simple. Simply identifying "what is whitespace?" is a big undertaking in Unicode.

Lua's philosophy seems to be to include the absolute minimum that is unacceptably painful to omit. This is a perfectly reasonable tradeoff for Lua's primary use case: embedding.

With respect to strings in particular, most systems that Lua is embedded in has its own string type, or inherits one from a framework. This is an unfortunate reality of the C/C++ world.

Returning to my point about language standard libraries: The lack of a traditional "standard library" is a feature for Lua, but only because Lua has a strong FFI and C API that acts as a "bring your own standard library" mechanism. It's less about needing a standard library, and more about admitting a language is only one piece of the puzzle. For a language to flourish, you need to have some story for interfacing with the rest of the world in a rich way.