Yes, that's it exactly. I've grown more and more averse to implicit state. I like that in Lua, all my interactions with the interpreter are mediated by the lua

Yes, that's it exactly. I've grown more and more averse to implicit state. I like that in Lua, all my interactions with the interpreter are mediated by the lua_State. If I want to run two at once, I can. If I want to store a Lua object for later use, I can stash it in there. If I want to have a globally-available state for my programs, I can implement it myself as a global. Nothing is mucking around with the call stack looking for things that "look like a pointer." A few years ago, I wanted to embed a scripting language into a monster of a multithreaded C++ application, which (oh joy) was using RogueWave threads rather than straight pthreads. I tried python, but couldn't figure out how to get the thread locking to work properly; python had its own ideas about how the threading should work. Then, I tried Lua. With Lua, I could just implement a pool of properly-initialized interpreters, then assign them out to each thread on need. It worked very well.