[aschampion]

Lua is great and generally the right tool for this sort of thing.

As an alternative, though, there are several Rust-based scripting languages that attempt to expose some of the power of the type system, etc., while being more amenable to dynamic loading, REPL, etc:

http://libs.rs/scripting/

[curun1r]

One that's not listed there but might be a good candidate for a Rust project is miri [1] since it's both interpreted and still Rust. It's still pretty rough, but the approach it takes should perform pretty well and won't require people to learn a new language.

[1] https://github.com/solson/miri

[stevedonovan]

It is outrageously fast (at least compared to compile) but would need integration via libffi to speak to the rest of the universe. This is not a priority for the maintainer, since he's exploring compile-time metaprogramming (where you want a very restricted sandbox)

[jamescostian]

Dyon (from that link) looks very cool! I'd also like to add that JavaScript is another language used in this arena, and there is a crate with V8 bindings (https://crates.io/crates/v8). Even Garry Newman (creator of Garry's mod) wrote that he believes JS would have been better than Lua for scripting: https://garry.tv/2014/08/16/i-fell-out-of-love-with-lua/

[talldan]

Unfortunately, some of those syntax niceties the Garry's mod creator mentioned are things that have been identified as leading causes of bugs.

++ mutates a variable in place, has non-trivial pre/post behaviour (many junior devs don't understand it), and its brevity causes it to be used inline, which results in complex one liners.

String concatenation using '+' is not considered to be a great feature in dynamically typed languages. When you can't guarantee the types of the operands, it can lead to unexpected results. Pass in two numbers, and it this returns the result of the sum. Pass in two strings, and they're concatenated.

'continue' is a strange one. I just don't use it, and I'm not sure why anyone thinks it adds anything. It's like an early return, in that it can cause some difficulty in code comprehension.

So it feels a little like Lua is being criticised for making some good calls.

[kbenson]

> String concatenation using '+' is not considered to be a great feature in dynamically typed languages.

Yes, one of the things Perl got very right, and yet it is still brought up by people as evidence of what makes Perl look like line noise (along with == vs eq, which is the same thing, even if the problem is less troublesome in that case).

> So it feels a little like Lua is being criticised for making some good calls.

All too often languages (and aspects of them) are criticized mistanely as being worse when all that is presented is how they are different. All too often we vilify the unusual just for being unusual.

[akavel]

As to 'continue', starting with Lua 5.2 you can actually simulate it perfectly with a

  goto continue

and then a

  ::continue::

slapped immediately before the relevant loop's end. Surprisingly, it's not affected by the rule forbidding "going into new variable scope" - because "the scope of any variable ends before 'end', wink wink, nice trick we left here for you no?"

[vvanders]

Yeah, Lua certainly has it quirks. However binding to JS is a huge endeavor. For instance that v8 crate doesn't easily expose a way to call Rust from JS which is trivial in Lua.

Also the JS runtime is huge and the build system is complex. You can run Lua in ~400kb or less and LuaJIT tends to walk over any other jitted interpreted runtime.

[strangecasts]

While the performance definitely doesn't compare to LuaJIT, Duktape (http://duktape.org/) could be a good target for Rust bindings - it's fairly small and available as a single-header/implementation library.

[steveklabnik]

https://crates.io/crates/duktape

[sitkack]

He even invoked Wadler's Law!

It really is too bad that JavaScript is different from Lua. Lua predates it by 2 years. [1]

Criticizing a language on syntax is something I would hope we could move past. Mr Newman didn't read about the history and purpose of Lua, otherwise he would know it was targeted at scripting data loads for simulations written in Fortran. Hence the 1 based indexing. Lua syntax is one of its SELLING points.

[1] https://www.lua.org/versions.html

[douche]

It's really too bad we don't use Lua in the browser...