Comment by matheusmoreira

> the hostility is present even at C-API level, with the stack approach

> Why?

I suspect it's because implementing control mechanisms is much easier when you reify the language's stack. Especially advanced ones such as generators and continuations which require copying the stack into an object and restoring it later. Making that work with the native stack is really hard and many languages don't even try.

It also makes garbage collection precise. Lua values in C variables would be placed in registers or the native stack. In order to trace those values, Lua would require a conservative garbage collector that spills the registers and scans the entire native stack. By managing their own stack, they can avoid doing all that.