Re: What languages could be used to implement the functions to be invoked by Lua?

[Albert Krewinkel <albert+lua@...>]

Francisco Olarte writes:

> On Fri, Sep 18, 2020 at 10:59 AM 孙世龙 sunshilong <sunshilong369@gmail.com> wrote:
>> As per the documentation(https://www.lua.org/pil/24.html), which says
>> that[emphasise mine]:
>> At the same time, a program that uses Lua can register new functions
>> in the Lua environment;
>> such functions are implemented in C (or **another language**) and can
>> add facilities that
>> cannot be written directly in Lua.
>> My question is what other languages?
>> Can these functions be implemented in C++? If not, is there any
>> workaround to achieve this goal?
>> If you could give some simple examples, that would be great.
>
> Once compiled, everything is machine code. You only have to worry
> about the calling convention ( where are parameters passed and how are
> values returned ).

I think this omits error handling and language run times, both of which
can be a challenge. E.g., HsLua, a Haskell wrapper around Lua, must be
very careful to handle errors at the language boundary. Assume a Lua
function `pcall`s a Haskell function, which then calls another Lua
function. If that last Lua function errors, then the Haskell runtime
system will be corrupted if we `longjmp` across language boundaries.

See <https://hslua.github.io> for a bit more info.

I believe languages like Rust and Go face similar issues.

--
Albert Krewinkel
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