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Rust Playground

play.rust-lang.org

98 pointstosh31 comments

The Rust playground is one of the many great things about Rust.

It's really helpful to share code and try concepts. The mere existence of the playground is a catalyst to reduce and refine problems before airing them to get help from the wider community.

Furthermore it's well integrated with the Rust community forums. The share button functionality is brilliant.

A minor quibble: its state management is not particularly intuitive. There's no notion of "save" or "branch" or versions as in Gists, for example. If there is, I haven't found it. The playground URL appears to be a hash of its contents? That's my guess. Does anybody know?

Code is here: https://github.com/integer32llc/rust-playground

> Does anybody know?

Yes, there's no branching for gists, but there are saves. If you hit "Share", you get various options:

* Permalink to the playground <- this creates a gist. URL is the gist hash.

* Direct link to the gist <- this gives you a link to the gist

* Embedded code in link <- this URLencodes the source and puts it in a parameter

* Open a new thread in the Rust user forum & Open an issue on the Rust GitHub repository <- hopefully self-explanatory

Looks like it's heavily inspired by the Go playground (which took it's inspiration also elsewhere, but afaik was a first for a compiled language).

There's always a trade-off between ease of use and flexibility, and I think the KISS principle is great for a tool like this. Never used it for Rust (only playing with it at the moment) - but in the Go world it's also referenced and used everywhere.

I really like to use CodeRunner for these types of purposes, I just save off the snippets of code into a folder so I can easily locate those ideas/thoughts/snippets later.

https://coderunnerapp.com

I wonder why we're seeing this on HN's front page now. Did something change recently in the playground?

Mostly because someone submitted it, then a bunch of people upvoted…

Kelsey Hightower tweeted about it. https://twitter.com/kelseyhightower/status/12812095507170713...

I disagree with the tweet:

> The Rust playground is pretty dope. D*mn near a full blown IDE running in your browser ...

I am not a fan of exaggeration. No, it is not ‘near’ a full-blown IDE.

That said, I think the Playground is wonderful, especially for a compiled language.

Agreed. Unless your only requirement for an IDE is text editing and a super convenient compile button, that’s a big time exaggeration.

Here is a common list of features that comprise modern IDEs:

  - edit multiple files
  - search across files
  - console/terminal
  - debugging
  - customizable keyboard shortcuts
  - source control integration
  - extensions/plugins

Optional:

  - long startup times
  - complicated and overly nested settings
  - run-amok CPU-hogging plugins

This misses "having an understanding about the source code and associated actions". Like refactoring helpers, autocompletion, etc. This is what distinguishes an IDE from a text editor for me.

But anyway, the Rust playground has none of those anyway.

I'd love a version that could pull in other packages other than the most popular 100 crates.

The cargo ecosystem is painfully getting a bit too npm-like and the top100 doesn't always have some basic needs.

> The cargo ecosystem is painfully getting a bit too npm-like

What do you mean by "npm-like"?

See Rust, upvote

One of the many stages of acceptance. It’s a long road. I don’t hold it against anyone.

Rust does sound interesting but I’m holding out until the job market begins to grow.

Corporate America tends to be slow in adopting new technologies.

Heck I think Java 8 is still the most popular version of a Java.

Something I really like about the Typescript playground is it has lots of examples with documentation and, not to put too fine a point on it, they all compile and run. Obviously this isn't designed for the same use case, but it'd be nice (from my perspective!) to be able to load in some example code that already works and doesn't produce an inscrutable (to a beginner) compile error.

I'm sure this would be a great resource if I did start trying to learn the language though, so thanks for sharing it :)

Yeah, the relationship is a bit different. In Rust, we tend to have docs that embed the playground or link to it, rather than having the playground link to docs.

Examples from the book shouldn't be too hard or at least some link to it?

Sure. Here's a random page on the book: https://doc.rust-lang.org/stable/book/ch08-01-vectors.html

You can click the arrows to run the code. This effectively makes an AJAX call to the playpen, and puts the results back on the page.

Here's a random page from the API docs: https://doc.rust-lang.org/stable/std/string/struct.String.ht...

Those "run" buttons will open up the example in the playpen so you can play around with it.

I think ideally these would all let you edit in place, run in the page, or open in the playpen, but they use slightly different tooling and nobody has put in the work to make it all identical yet.

Output of the default code in the app generates errors:

=================

   Compiling playground v0.0.1 (/playground)

error: unexpected token: `...` --> src/main.rs:13:15 | 13 | for x in 0...10 { | ^^^ | help: use `..` for an exclusive range | 13 | for x in 0..10 { | ^^ help: or `..=` for an inclusive range | 13 | for x in 0..=10 { | ^^^

error: aborting due to previous error

error: could not compile `playground`.

To learn more, run the command again with --verbose.

I've wanted to turn some students onto Rust, so I tried to give them https://github.com/rust-lang/rustlings loaded into a repl.it account -- but the way repl.it works breaks rustlings in multiple ways.

I'd love if this Rust playground could eventually provide that experience.

I appreciate the vi mode editing. `:w` will compile and run the program, but that is the only colon command I have discovered.

It farms out this behavior to the Ace editor it uses. I'm not sure what all it supports, but that's how you'd figure it out.

Thanks for the tip! If anyone is curious I found the list of commands here: https://github.com/ajaxorg/ace/blob/master/lib/ace/keyboard/...

Compiler Explorer lets you see the generated assembly code, if you're into that sort of thing. Supports loads of languages and compilers too!

https://godbolt.org/z/qM67Pe

Playground also provides that feature, but it doesn't clean the assembly as well, nor does it provide side-by-side view and coloration.

Dropdown menu next to run, select "asm".

Is there a way to browse what's in it? I'd like to see how people write Rust.

There is not, mostly because nothing is “in it”; any persistent state is farmed out to localstorage or gists, as far as I know.

Usability significantly decreased - now you have to go into menus to do anything. Yes, the interface may look cleaner, but you are not supposed to admire playpen visuals, you are supposed to press those now hidden buttons first of all.

I think the discoverability has increased, though. There are multiple ways to "run" the code, all next to the "run" button (which will automatically change to "test" if you put tests in your code), and compilation options are next to that. Stuff like Clippy and Rustfmt is in the "tools" section.

Does it not work in incognito mode? the compiler reaches time out with the println!("Hello, world!") example

Edit: reloading the page fixed it.

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