Wren: A classy little scripting language

85•Lyngbakr•4d ago

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gnabgib•4d ago

Popular in 2022 (301 points, 130 comments) https://news.ycombinator.com/item?id=32631553

2020 (122 points, 54 comments) https://news.ycombinator.com/item?id=23660464

apitman•2h ago

I was working on a custom runtime for minimal wasm apps recently. I didn't want to have to write all apps in C or Rust, so I went looking for tiny scripting languages. Lua is pretty small, but I wasn't able to get it to compile to wasm IIRC due to POSIX dependencies. This turned out to be quite easy with Wren[0].

[0]: https://github.com/wren-lang/wren/issues/1199

MattJ100•1h ago

That's unusual that you struggled to build Lua. Lua is primarily C89, and used on non-POSIX microcontrollers for example. There are some optional bits of the standard library you would have to leave out - module loading uses dlopen(). This is done simply by defining the right feature macros for your target environment: https://www.lua.org/source/5.4/luaconf.h.html

You may also be interested in this project: https://github.com/fengari-lua/fengari

sandbags•2h ago

I would love to replace JS as the scripting language in one of my native macOS apps and I wonder if Wren would be suitable.

The two biggest questions I’d have are:

1) how easy it would be to bridge Obj-C objects to Wren-space and vice versa (a big win of using JavascriptCore) 2) how easy would it be to implement script debugging? This is not exactly a strength of Javascript core but it is at least possible by connecting the Safari web inspector.

There’s lots I don’t like about JS and JSCore but i’ve yet to find a better alternative.

reactordev•2h ago

This looks super cool up until I got to the point where it says inherited classes don’t share the same metatable. Meaning if you want to provide the same method on your inherited classes, you have to write the same thing and do a super.method() which means a lot of work if you’re into OO design so I’m not sure if classes is the right construct here. Am I wrong or did I miss something from the documentation? Other than that it looks like fun to use as an embedded scripting engine.

nick__m•1h ago

you probably meant metaclass and according to the doc classes inheritance don't have surprising behaviors. And about the metaclass not being inherited here are the implication:

  ...In more prosaic terms, this means that static methods are not inherited.

plainOldText•2h ago

Reminder the creator of Wren wrote the awesome Crafting Interpreters book [0].

[0] https://craftinginterpreters.com/

l9o•1h ago

This is awesome. Thank you for sharing. I have been working on a small interpreted language for shell scripts with lots of help from Claude Code. The main idea is to automatically generate the cli interface for the scripts based on function definitions. However, I'm far from a programming languages expert, so I've been a bit hesitant to share my work. Going to give this book a read this week to see how far I am. Thank you!

manveru•45m ago

Take a look at how Nushell does this, it's quite neat: https://www.nushell.sh/book/custom_commands.html#documenting...

l9o•42m ago

That's excellent. Somewhat similar to the syntax I went with, but most likely much better implemented. I'm going to give it a go. Thank you!

mhaberl•1h ago

and he wrote Game Programming Patterns [0]

[0] https://gameprogrammingpatterns.com/

ronbenton•1h ago

Knowing this is the author makes me 1000% more interested in Wren. What a great book!

thw_9a83c•57m ago

It is an excellent book and one of the canonical texts on the subject. My only suggestion for the "Lox" language would be to include an implementation of arrays, and preferably also hash/dict arrays. Other than that, the book contains everything you need to know about implementing a programming language.

smnplk•6m ago

I wish he would have used C for everything. You need to buyin into Java's whole OOP thing, which I am not a fan of.

alberth•56m ago

Is Bob still involved (in Wren)?

I thought his focus was Dart these days given being employed by Google.

bragr•1h ago

This seems like a nice alternative to Lua. I've always liked embedding Lua in other software, but I confess I have never really liked Lua as a language.

versteegen•54m ago

I really like the sound of Wren, but you may also want to look into Squirrel, it's basically Lua re-imagined/reimplemented but without all the Lua quirks and with C-style syntax (but it still has optional lua-style prototypes, which means it ends up very similar to Javascript). Its embedding API is largely a copy of Lua's. There is also an active fork called Quirrel that makes the language more like Python.

There are loads of scripting languages but very few of them have an embedding API as powerful as Lua or Squirrel's. (My benchmarks: what's the overhead of a userdata pointer? Is there a proper debug API? Can you suspend a co-routine from inside a called C function? Very few languages even have coroutines.) Last I looked at it years ago, Wren was one of the best. Of course, the most featureful embedding API of all belongs to LuaJIT.

tromp•1h ago

Wren ties with Phix for most tasks done on Rosetta Code [1].

[1] https://rosettacode.org/wiki/Rosetta_Code/Rank_languages_by_...

davidw•1h ago

Looks very nice! Erlang's concurrency isn't 'cooperative' though - it has a scheduler, so even a runaway process won't bog down the whole system.

gabrielsroka•59m ago

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