I agree it would be great to see this repl running 100% in the browser!
The stability of the compiler endpoint/service is really finicky, and it performs poorly (those could both be related to load issues, maybe it's just front-HN-page syndrome). Not sure if it's possible to replace it with another one or try hosting your own perhaps?
The code transformations are really unpredictable. Sometimes it asks me to copy/paste code, sometimes it starts with its own version of the code. Sometimes the next step "undoes" my fixes (I know Rust so I was "rushing" ahead with some changes, which is my fault). There's a few ways that could be done here, but IMHO the best would be to have a "use this snippet" button and to just not touch the code from the previous step. If the lessons have chapters and you want to set up the editor for the user, that's fine, but make sure it's obvious someone's moving onto the second chapter of the tutorial. At the end of the day, if you choose to just have manual copy-and-paste (the least ergonomic choice, IMO), that's also fine, but just make the experience consistent and predictable.
The layout is extremely disorganised on the page. There's a giant disconnect between the console, the editor, the run button, and the hints, and the test results. There is no well-defined user flow on the page, interactions feel very erratic. I can't offer any ideas here for how to fix the layout, because it will get very wordy. To sum it up though, the page needs more structure/hierarchy. This will also create space on the page, so you will be able to use some whitespace/negative space to create hierarchy too (it's a bit of a chicken & egg problem lol).
Lastly, the "checkpoint" doesn't always pass when it probably should, because there's no hint as to why it didn't pass, apart from a compiler warning. The compiler warning is important and should be fixed, but a couple of times it was simply because the injected snippet came with "previous" problems that distracted from the step/instruction at hand.
I can't really comment on the quality of the tutorial since I stopped after 16 steps; I couldn't keep going any more because I was incredibly worn out by the poor UX. Proceeding to the next step was was always some struggle in relation to UX, and not the content of the tutorial.
With that said, some things for content until step 16, I think some concepts are a bit inaccurately explained, but I suppose one could let that go because you wanted to keep the tutorial short.
As for the unsolicited feedback, thanks!
I realised later that I can jump to lessons, so I skimmed what the rest of the content is. I think content wise it's good. Given its "Rs for web devs," my comment about inaccuracies might've been unfair. I assume the lesson meant to be bite-sized and playful/exploratory. So, its in a good format for that.
I'm still rooting for Rust, but it's not for everything (yet).
Many people just go RC<> but then you have RC<> everywhere.
I do understand the motivation to have lifetimes and no GC, and it's cool, but it makes things that are trivial in a language with GC often difficult in Rust (the problem might be with me only as I've stopped working with C around 1995 and have been on GC/automatic RC since then, starting with Perl).
(Not the previous commenter, yet thought this context was the most relevant)
However it is cool to see so many Rust posts recently. Or maybe I am noticing them more since I am getting into Rust.