Maybe that explains it. What I mean is things like Lua doesn't have a popen in its standard library that lets you both read and write to the subprocess, because

Maybe that explains it. What I mean is things like Lua doesn't have a popen in its standard library that lets you both read and write to the subprocess, because there's a case where this can break (if what you're sending over the pipe is bigger than some internal buffer). Ruby and Python both let you do this, even with the potential for breakage, but Lua prefers correctness over convenience. A lot of the library calls in Lua seem closer than I'd prefer to the underlying C, because they don't want to provide abstractions over it that could break (even if the case where it breaks is something you'd never do). I guess this is because they don't know where it could end up getting embedded, but that kills it as an everyday scripting language for me.