I have embedded Ruby and Python before so I found that paper interesting to read. Wish there were mentions of languages I'm unfamiliar with (eg: squirrel, javascript). Anyway, I appreciate the design decisions and no doubt Lua has merits, but my personal experience is I haven't found it to be a pleasant language to use or embed.
Garbage collection is a controversial topic too, and if I understand correctly, a part of the reason Lua has a stack based API (with how its GC works). I somewhat liked the level of control I had with reference counting from working with CPython. Some applications may even go out of their way to disable the GC and use weak references to guarantee determinism similar to Apple's ARC. Squirrel, born as a competitor to Lua, looks to use a GC approach similar to Python at a glance..
Garbage collection is a controversial topic too, and if I understand correctly, a part of the reason Lua has a stack based API (with how its GC works). I somewhat liked the level of control I had with reference counting from working with CPython. Some applications may even go out of their way to disable the GC and use weak references to guarantee determinism similar to Apple's ARC. Squirrel, born as a competitor to Lua, looks to use a GC approach similar to Python at a glance..