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Okay what is going on in Japan and why are so many Tokyo workers running around grabbing futures. I just woke up and I'm half asleep and RUclips autoplay this and I do not understand anything that is being said. Who is waking up Japanese poll workers and why?

This is one crusty corner of rust.

The reason that the book includes the original string in every token is basically only for error reporting. With miette you handle all of the necessary state to track that during iteration, so it would probably be reasonable to only save anything for idents, numbers, and strings. With that you could keep everything in TokenKind. Actually on second thought, that doesn't really work until you get to the compile-as-you go bytecode interpreter, you lose your original place with runtime errors in the tree-walk interpreter. It could be an interesting exercise in how to make it more "rusty" if you get to the bytecode section, I guess.

1:20:00 this hack to satisfy compiler are pretty crazy

20:27 - Cat confirmed employed. Better be paying a decent wage man, they be hungry out here on a budget 😂😂😂❤

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1:15:36

Around 5:00:00; parsing things like ‘for’ and function calls as a special type of operator reminds me of a more general idea from some functional programming languages - particularly interactive theorem provers like Agda and Coq - called *mixfix* operators. In that setting, you can have an operator like ‘if_then_else_’ which is a prefix operator with two ‘internal arguments’, with the positions of the arguments specified by the _’s. This isn’t something that can be handled by basic Pratt parsing though, and most of the implementations out there go the extra step of allowing user defined operators too, so it’s definitely overkill for this project!

Regarding the first Q&A part (about 20 minutes in), the way I'd explain bytecode is that it's machine code for an ISA that doesn't physically exist, but instead is implemented in software, and that implementation can then be through e.g. an interpreter or a JIT compiler.

Decrust ratatui please

Another common case to use JoinSet is: when you have separate tasks doing their own thing, but want to kill all of them if one of the tasks errors out. E.g. you have some receiver task, which pushes data to some/multiple processor tasks and you have a signalling task, which waits for external commands and/or interrupts. If any of these tasks completes you want to be able to shut down the rest and maybe restart the whole thing

I've been playing around with a parser style where the state machine is more explicit, e.g. with immutable state and functions LexerState -> Result<(Token, String), E>, and where you combine and compose those functions with monad language. Which is really cool, but then I took uncomfortably long to write out a sexp parser, and I decided I wanted to get back to the basics for a bit. Good old ~linear parsing, no big lookahead/backtracking, but still with good type safety, healthy memory idioms and good error reporting. Plus I haven't touched Rust in a while, so this video is the perfect excuse. Thanks for the videos as always, they rock -- hope we get a part 2 for this one!

3:14:26 i think we need ...or_else(|| self.rest.len() -1). Otherwise my code crashed, when the comment was the last line

At 45:14 - 48:00 you talk about shutdown, and unless I misunderstood the documentation you make incorrect statements. for instance: when the main future exits, the OS does NOT immediately shut down all the threads - from the docs: 'Tasks spawned through Runtime::spawn keep running until they yield. Then they are dropped. They are not guaranteed to run to completion, but might do so if they do not yield until completion. Blocking functions spawned through Runtime::spawn_blocking keep running until they return. The thread initiating the shutdown blocks until all spawned work has been stopped. This can take an indefinite amount of time. The Drop implementation waits forever for this.' also, shutdown_background & shutdown_timeout do NOT shutdown gracefully.

yeah. to switch text from upper to lower case or vice versa you can use gu or gU optionally you select using a motion and apply it on selection.

Very cool! You inspired me to try the CodeCrafters challenge myself, and just completed the whole thing... Alas, the CodeCrafters site only goes up through basic statement evaluation with global variables, and doesn't cover the rest of the book. I suppose nothing is stopping me from continuing on myself, though. Thanks for doing this! It's fun to see how different our approaches were.

Did you ever find out who was committing to your repo?

Why don't you use some darkmode extensions?

This was really fun, personally I'd love if you added more "best practices" / convenience crates like camino etc. as I feel a lot of the educational value comes from seeing how to do things well. E.g. all the work on the Iterator that uses references to the source string is much more useful to see than just cloning the string as you go character by character.

A really small query: when Jon said, "... as you get characters from the input you produce tokens from the output...", at ~52:22 did he mean you produce tokens for the output? Just new to this and want to make sure I haven't missed something about how input/output interact.

Just saw that you were one of the magicians who wrote The Missing Semester Course too. You have put out some incredibly useful resources.

Pratt parsing for statements seems like huge overkill. Just match on the first item, if it's a keyword handle that particular form, if it's not, go to (Pratt) parsing expressions. Pratt parsing's win is handling all the nesting and recursion and you have none of that at the statement or block level. Notably, there is no binding power at the expression or block level, so you don't need to pass around r_bp everywhere.

Python's CPython doesn't do JIT btw. Though it does have alternate interpreters that do JIT (pypy)

You're killing me with the light mode, Jon. Great content though.

You are such an amazing teacher. Thanks so much for everything you have done.

I love the 'Implementation' videos from you Jon, keep up the good work! 💪🏾

Awesome content! This is what Tech RUclips needs more of.

00:00 my eyes are toasted from that light theme

Naruto whirlpools, Rasengan, I'm in 🚀

My cat mauls me when i try to get it to switch to rust from C

hi, jon, it seems like the parser isn't fully complete, will there be another stream about this?

The link to matklads article in the desription seems broken, I get a 404 on github pages. I think youtube parses the parenthesis as part of the link, the irony!

Please make more such projects building in Rust with industry practices.

Small correction: cpython (the python interpreter) is indeed a bytecode interpreter, so there is a compilation step that goes from AST to a bespoke bytecode instruction set. Old versions of ruby and perl are a better example for tree walking interpreters, as they run directly on the parsed AST (even though I believe modern versions also compile to bytecode for efficiency reasons)

1:00:29 I always thought you couldn't have multicursor in nvim? Is this a plugin? I've been using multiline selection with :s/find/replace in these cases.

Why are you adding so much unnecessary boilerplate and being so fancy? One of the reasons I started liking zig more than rust is because I've seen in a lot of rust projects with crazy amounts of abstractions, unnecessary type wrappers and misdirections where I can barely follow the code.

Super cool, thank you for making this! Can't wait to get through the video. I took a crack at Crafting Interpreters in Rust earlier this year, it was a lot of fun. Now I'm setting an early new year resolution to build a Hindley-Milner, LLVM based language (in Rust, of course).

Always learning more concepts about rust. Appreciate a lot from Kenya . Though I could suggest for a copy of your book 😊. I’ll appreciate a lot.

It was incredible useful, thanks very much!!

I would describe Java enums like this. The enum declaration declares a type, and the options within an enum are instances of that type. So, each option has to have the same set of data.

Thank you for that tutorial... Very helpful to understand all background of this :)

Great content! Your thoughts on using sponsorship to create more content to be available for free resonates with me. I have the same principle for my content- I just haven't set up a sponsorship pipeline yet. If you're ever looking to collaborate on content or just chat technology happy to do so! Subscribed for more.

Is anyone able to tell me whether anything has changed with async/await in rust since this video? Just wanting to confirm before committing the time

Pretty new to Rust and don't really have any async/await requirements or anything, but I've always wondered how it worked under the hood. This was the perfect video for learning, thanks so much 😄