Rust Demystified 🪄 Simplifying The Toughest Parts
ฝัง
- เผยแพร่เมื่อ 10 มิ.ย. 2024
- Rust can be frustrating to learn even for developers with years of experience in a language such as Java, JavaScript, or C++. But most of the friction in learning Rust comes from a few core concepts that don't really exist in any other language. These concepts are what gives Rust an edge over other languages. Once they are understood, the Rust journey becomes a lot easier. Moreover, these concepts aren't hard to understand when they are presented using the simplest example possible.
00:00 Introduction
01:41 Ownership and Why
02:46 3 Alternatives To Ownership Changes
05:36 Mutable References
07:45 Lifetimes
11:54 Struct Lifetimes
13:30 Conclusion
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ERRATA
* I mention that you get a segfault when you don't deallocate memory in C/C++ - I meant to say that you get a segfault when you try to reference memory that was already deallocated. Not deallocating memory will lead to memory leaks in some cases.
nah still,, a banger video
@@raiyanahmed3534 thanks!
It's not generally true that accessing deallocated memory causes a segfault either. Actually, it would be more helpful if that was the case, since it would be easier to debug than the case where your program is silently accessing data that may or may not be garbage depending on the execution state.
dammit I was gonna yell at you :)
Many embedded systems just use static allocation, so you never deallocate by design.
you dont get a segfault if you dont deallocate memory. Segfaults are when the kernel informs your process that you accesed memory you shouldnt have
ugh, you're absolutely right! This was an egregious mistake. Not deallocating will result in a memory leak. I meant to refer to the case where we erroneously deallocate memory and then try to reference that memory. I'll put a note in the description, thanks for pointing this out!
yo ucan also segfault by accessing memory you never had access to. (in most cases..)
@@GottZ yes I never said that wasnt the caes, I said purely deallocation alone doesnt provoke a segfault directly
@@codetothemoon Also, you can segfault if you correctly deallocate memory and then (because you had more than one reference) you deallocate it again and corrupt the malloc recordkeeping. Sometimes this takes quite a while to blow up on you!
you segfault every time you run your c program for the first time
I like what you are doing here. I am glad that No Boilerplate is influencing people because I am sick of all the stupid presentations in other channels. 1 minute of BS, songs, animations, and people presenting their channels and welcoming as if we were 6 years old watching Ryan's toys reviews.
Thanks! re: the filler stuff - yeah I'm not a fan of lengthy introductions either. I'm not entirely above obnoxious animations (see earlier videos) but I definitely like to get to the point 😎
7:44 In case anyone is wondering why the mutable reference will work if you remove the last `print_some_struct` which uses an immutable reference.
This is because of NLL (non-lexical lifetimes). In short, the compiler infers that it is able to drop the immutable reference borrow before it gets to the mutable reference, because it's not used anywhere later. Thus, you only have one mutable reference, which doesn't break any rules
Great, as if Rust hadn't gone out of it's way to make things confusing already they don't have NULL, they have NLL. I'm half convinced this is intentional at this point and this is all just some cruel trick by some trickster diety of programming to make an incredible language that is intentionally designed to drive as many people as possible away from using it. Wait... trickster diety, Loki - Odin lang, Odin... checkmate athiests.
It's good you mentioned this. This confused me for a long time.
I was learning Rust for some time now. I already understood borrowing and the entire ownership model really well but didn't admit I don't get lifetimes at all. Today it finally cliked for me (after 3 months of learning rust :D). It was so obvious and under my nose the entire time! Thank you very much for your amazing explanation! I am incredibly excited to finally dive into Rust completely.
Nice, glad you found the lifetime explanation helpful! I wasn't 100% sure if my explanation was as straightforward as possible, so this anecdote makes me very happy.
Your videos on Rust are well explained and to the point. Plus with the production quality of these video's, it will only take a matter of time before your channel blows up!
Thanks for the kind words Brunkel! I aim to make videos that are engaging but still pack in as much value as possible. I'd love to do this as a full time job, I appreciate you watching as it really helps me toward that goal!
Every new rust developer should watch this video,very effective as always.
Thanks! I really do hope this can be a resource for newcomers that removes as much of the friction as possible.
@@codetothemoon it really does XD. I'm eager to learn rust and this video made me more interested. this video is pure gold.
from the bottom of my heart: thanks you
Would like to see one on Procedural Macros as well. They are essentially magic to me right now.
Great idea Soumen! In fact I have this in the works already, it might be the next video.
Macros are the reason I immediately stopped using Rust after learning it through their book.
I knew how to code in Rust, wanted to build something and suddenly nothing made sense anymore because everything was obfuscated by these stupid magic Macros. But apparently that's just something you have to deal with, some libraries just don't want you to know what's really happening.
@@marl3x I think its ‘cargo expand’ which can be used for printing the result of macro expansion in a given program. I think the library developers are prioritizing usability and small code size over understandability, which sadly sometimes are tradeoffs
@@marl3x I don't think I've ever used any third-party macros, only the ones from stdlib and my own. As Rust docs for libraries are auto-generated from code they contain everything either way, so you can usually avoid macros. I know some libraries separate their macros into another optional package as well.
@@marl3x I'm using Rust for years already and I almost never come across libraries, which use macros.
I also don't use a lot of macros myself.
Almost always, it's been macro specific libraries. Mostly custom derives.
If one uses macros, it's not about not wanting the user to know, what's happening internally, it's a simplified syntax for a special purpose.
But I also don't like, when I see a library, which forces me to use a lot of weird macros.
I've watched many channels, but yours is by far the best explanation style I've seen so far! Kudos bro.
I just started learning Rust a couple weeks ago and decided to build a calculator in a Yew app. Finally got it up and running last night. I was excited about the ownership concept for similar reasons to what you described due to enormous frustration with trying to rebuild Javascript after encountering runtime errors on runtimes I couldn't test in the development phase. Turns out, it made the calculator thing easier rather than harder by some miracle. I did run into some pretty confusing lifetime errors though. You have to be super careful where you declare things and how long you keep them around, but if you can do that, you're pretty much gold. The whole process for building and deploying a Yew app was a fair bit more enjoyable than React as well. Definitely nicer than wrestling with node_modules.
Nice Andy! I love hearing stories like this. I imagine others will have similar experiences
Magicccc!! we need more of these short videos. Great job :)
Thanks void, more to come!
This was my second rust video I’ve watched and as a senior coder even I’m amazed at the level of thought that has gone into the language.
I agree! As with any language, there are some aspects I don't like but it's really incredible what the language has accomplished!
I definitely got tripped up when first encountering the syntax and explanations around this in official docs and other resources. You really broke things down in a beautifully comprehensible way. Thanks so much for the vid!
thanks, really happy you liked it!
Wow, this is a brilliant video! I had some trouble with the borrowing, but now I've got it, thanks to you! 💡
fantastic, really happy this particular approach made things clearer for you!
Very clear explanations and straight to the point. This the best 14 minutes of my rust journey so far.
thank you, glad you got something out of it!
This was great, I love how you gave actual examples for the things the compiler was complaining about.
Thanks Gazareth, glad you found it valuable!
Nice. Really love how clearly you explained the concepts - especially the WHY as that makes it easier to peer behind the compiler and understand what's happening - ESPECIALLY with Lifetimes. I'll have to watch a few more times for it to burn into long term memory, but this is the first time I've understood lifetimes 😂
thank you, really happy you got something out of it! i felt like so many people get stuck on these concepts, and there was an easier way of approaching them...
Incredibly easy to understand and straight to the point video, keep up the good work!
Thanks, glad you found it valuable!
Very good tutorial. I had trouble with moving playing with Rust and despite understanding somehow how it's working, this explains the basic concepts very well. Thanks a lot
nice, really happy it was helpful!
So much effort to return a variable!
hah! luckily it's a bit of a corner case...
this really helped me a lot understanding these concepts. ...huge THANK YOU!!!
glad you found it valuable, thanks for watching!
Good stuff :), though your explanation of copy was a bit lacking, it's not just that it's implicit it's also that it requires the memory copy-able one to one, this works great when you have a struct full of primitives since copying the memory is fast, however if your struct contained pointers to heap memory such as box or vec then you wouldn't be able to implement copy since just copying the memory would create a cloned object with the same references.
Furthermore copying the struct especially when it only has 1 primitive field is a zero cost abstraction and so it would be no different than giving the print struct a reference.
Jannick - you're so right! Thanks for pointing this out. I'm going to start an errata post and mention this and the incorrect statement I made about segfaults in C++...
Great pacing and presentation - quickly becoming one of my favorite Rust channels
Thanks for the kind words! If there are any topics you'd like to see let me know!
@@codetothemoon these might be a bit niche, but here are a few things I'd like to learn more about in no particular order:
- speeding up python code using PyO3
- high-performance/multithreaded data processing with ndarray and polars
- speeding up a React/Svelte SPA by writing expensive business logic in Rust and compiling it to WASM
- The current status of WASM/WASI and when to expect WASM to get better at DOM manipulation
Amazing just got fed up with JS for the eleventh time this week and started reading rust docs and now this, thanks!
Thanks Tobias, I really appreciate you watching each video!
Thank you. Amazingly explained.
Very clear explanation. Thank you.
Thanks for watching Tuan!
These were indeed exactly the parts that were hard to get used to as someone who is used to GC collected languages. Very useful tutorial.
Thanks Qaz, glad you found it valuable!
Great video! I really feel like I've understood borrowing and lifetimes for the first time since the first time I was rust-curious a year ago
Thanks Pat, really happy this helped clear up the confusion around these concepts!
Thanks for all your explanatory videos on Rust. I am learning just as much I should from videos without the becoming tutorial dull.
I had one question, which I later checked on my own, shouldn't you have removed Clone and Copy Derives after there work was done, it would have removed unnecessary confusions.
Keep making these learnable videos without making them into dull tutorial. Thank you again. ❤
I started learning Rust a couple weeks ago and had a hard time grasping the concept of Lifetimes... which now I do because of your video! Great content 👌Thanks a lot !!!
Nice Jorge! Glad you found the video helpful!
Another great video. Lifetimes have been giving me grief and this helped. With 40 years experience programming in at least a dozen languages, these really are the somewhat unique and challenging bits of Rust.
Thanks Rich, really happy you found it helpful!
Excellent explanation!!! keep doing more videos like this!!
thanks, more to come!
this was a very helpful video. i already knew how to use lifetimes because i got used to them, but i couldn't have explained how they work. now everything is crystal clear. keep up the good work!
glad it was helpful, and thank you!
Just the video i was looking for ...awesome!
thanks, glad you got something out of it!
Excelent explanation!, really loved it! it's very concise and to the point
Thanks Luis, glad you found it valuable!
Very well delivered and easy to follow! Thank you!
thanks maxreuv, glad you found it valuable!
This was incredibly useful, thanks a lot!
nice, really happy you found it valuable!
Thank you for the indexed video!
Thanks for watching Jambang!
Thanks for demystifying the lifetime concept. What I didn't get up to this video, was that you introduce the lifetime *in the function* as some form of a guarantee about the variables not going out of scope, but it is the *caller* of the function to make sure this guarantee is upheld .
I would love a bigger video on this with a focus on examples! Great vid
Thanks, bigger examples are on the way!
I have finished the Rust book along with rustlings exercises, which I cannot recommend enough to everyone who wants to learn Rust. But this video was so great at solidifying the concepts I learned! Please do more content like this! *subscribed*
The Rust Book is fantastic! More videos on the way. Very Happy to have you onboard!
What's wrong with rustlings? I wanted to try it.
@@egorandreevich7830 Nothing, rustlings exercises are wonderful
@@mbrav so why you cannot recommend it?
@@egorandreevich7830 I cannot recommend it ENOUGH. Meaning is inversed.
I think I finally understand lifetimes. Simple and elegant. Thank you!
Nice, glad you found the video helpful, thanks for watching!
Thank you for this! I really love your content and would like to see more.
Thanks for watching, more is on the way!
Thank you for such clear explanations !
Thanks, happy you found it valuable!
The thing about Rust is it is an incredibly deep and powerful language. And for good reason. But that means that it will take longer to learn than many of the most popular languages out there today. So the productivity curve for a new developer will start off relatively slow, but as they gain experience eventually they will end up being able to build things much more quickly and much higher quality than in other languages.
agree! 💯
that's pretty much the same with other languages, like C++ for instances. You start slow that when you gain understanding and experiences your productivity will rose
Great video. You just made me to try clean my laptop screen with that grey line on your camera background 😅.
Thanks and hah! Green screen keying is tricky to get exactly right sometimes.... 🙃
Shows why I like languages with GC so much.
(defn bigger [a b]
(if (> a b)
a
b))
(bigger 3 5)
Done. Depends of course on which you prefer or need for the use case: developer performance or code/app performance.
Loved it, thanks for the explanation
Thanks for watching Abishek!
Very well explained, thank you!
Thanks for watching, glad you found it valuable!
Great video. Really clear explanation.
Thanks, very happy you found it valuable!
I've finally understood it! THANKS
nice! really happy you got something out of it!
Very helpful video. Thanks alot.
thanks for the clear and concise video!
Thanks Carrot! It'd be fair to attribute at least some of that clarity to your abundant levels of vitamin A!
Thank you this helped a lot!
Nice, glad you found it valuable Abhinand!
Killer video. Bet this guys channel blows up if he keeps making content in this style
Thanks Jacob, I hope you're right!
Thank you so much! I've finally understood the lifetime.
Thanks for watching Chan, glad you found it valuable!
simply and useful. thank you
nice, glad you got something out of it!
Thanks for amazing explanation.
very happy you got something out of it!
The borrow checker makes so much sense, it's surprising that it never got popular before rust. Rust makes me think about memory and types, and the compiler ensures I mostly make correct choices. It feels awesome.
I agree! it's interesting how many recent innovations in software (like the borrow checker) are completely independent of modern hardware and theoretically could have been discovered decades ago. Blockchain and Transformers are also great examples.
Very good video for beginners, i would have liked to see it myself a bit before, when i was struggling to understand and use borrowing and references, but it did make me understand lifetimes well, very good job !
thanks ziii, glad you found it valuable!
This channel is a blessing
Very happy to have you onboard!
Excellent explanation!
Thank you, glad you found it valuable!
Great explanation. Thanks :)
thanks for the kind words, glad you got something out of it!
Great little vid, thanks.
Thanks for watching Neil!
Thanks. Very helpful.
Really it's a great video , keep going and we wand bigger projects 💙🔥
Thanks Hamdy! Bigger projects are on the way!
I believe the issue with Rust lies not in a lack of understanding about how ownership works, but rather in people's struggle to navigate the limitations it presents. It would be wonderful to come across a video showcasing real-life examples of potential problems and effective strategies for mitigating them.
Yeah I think you're probably right about that. Maybe check out this video on interior mutability - th-cam.com/video/HwupNf9iCJk/w-d-xo.html it might have what you're looking for
The cleanest explanation I've seen on YT.
Thanks pvc!
this is explanation to the moon. Keep the tutorials coming. Thanks :)
glad you found it valuable, more are on the way!
Thanks for this video. I tried rust for a while and basically just fumbled with references and lifetime definitions until it did what I want. This video does a good job showing what each of those concepts is so I can be deliberate about my code next time.
nice, really happy you got something out of the video! 😎
Good explanations. Recommended.
thanks, glad you got something out of it!
Thank you for your videos! Really want to watch video about traits and derive from you.
Glad you found them valuable! I'll put traits and derive on the video ideas list!
Thank you very much that helped me a lot
I learned this ownership & borrowing system (as well as most of the things I know about rust (not a lot)) by making a Compiler for a language that also uses that so I wrote some simple Rust code, compiled it to LLVM IR and tried to understand it. Best learning technique👍
Coming from C++, there are some analogous patterns. But, it's nice to have the patterns enforced by the compiler.
perfect explanation, thank you!
thanks, glad you found it valuable!
This is very helpful. Thank you!
Thanks Cody, glad you found it valuable!
in rust, when instantiating a `struct` , on the stack, is the variable that we declare is actually a pointer in disguise which also points to data on the stack. like in @1:44. Because, here there is no mentioning about the data (i.e `SomeStruct`) is passed as a reference or by value to the function `print_some_struct`. What we all know by default the data is "moved" to the function, and so the pointer that is initialized earlier is invalid after the function exit (or return).
It might also be important to note that & references aren't immutable references, they're shared references. The reason these are not being called "immutable" or "read only" references, is in fact because you CAN mutate through them if it's an interior mutable type. (Mutex, RefCell, Atomic types, etc). In these cases, the underlying type ensures that any concurrent access/mutation to the data is safely done.
And &mut references are exclusive references (which as you surmised are mutable in this case, that's why they're exclusive).
Crystal clear explanation. I tried to learn rust a while but everytime I came across borrowing errors I got frustrated and ended up not persuing rust. Maybe after this video I will try again
Thanks Nova, glad you found it valuable!
You are amazing! Thanks for the great content! 😊
Thank you so much for watching!
great info, cheers
I take it that, when calling a function with a non-reference argument, the memory used is "moved" from the caller's stack frame, to the called function's stack frame. When the called function returns, without returning the argument, its stack frame, and the argument, disappears. If the argument points to non-stack memory, that memory is cleaned up as part of the called function end.
thanks so much!!😍
thanks for watching, glad you got something out of it!
hey you are great buddy thanks for this!!
thanks for creating this video, i undestand mostly lifestime and reference, borrow is still shallow to me, i started to lean rust, read a few paper of the rust doc, maybe should start writing some simple program to learn those concept
excellent explanation, one of the best so far 👍🏻👍🏻👍🏻
Thanks Hans, glad you found it valuable!
thanks a lot for making this
Glad you found it valuable!
There are at a lot of other memory save languages, and they are also fast. However, their builders are more focused on optimizing compiler speed and less on internal quarrels.
Great video, I think you should have also explained here about non-lexical lifetimes (at 9:20 you used `bigger` on line 25 to prevent its NLL, but this can confuse many beginners as to why some scenarios don't give an error when you said they should), and also slices (I was very confused about them as a beginner)
Great points - I'd love to go into lifetimes in more detail in a future video. Slices too!
great job 👏🏻
Didn't realize derive clone was making a copy every time I was passing it to a function call. Oh dear. Should probably avoid that in embedded code. Haven't come across lifetimes yet in my own code, but this was very helpful to understand how they should be implemented and why.
Yeah definitely something to be careful with for performance critical apps... I've only had to deal with struct field lifetimes (which I feel like should be inferred by the compiler instead of needing to explicitly specify) in my real world Rust work - haven't had to do it for function parameters yet. Seems like it's not a common need.
This is so easy for people who worked with pointers before. Really says a lot about the state of programming nowadays
glad to hear that it's easy for some - I personally found it a bit challenging to grasp at first despite having substantial C++ experience
@@codetothemoon Maybe because you don't had anyone to explain it to you through examples?
Best Video today! You are a king! Will try rust again...
Thanks Zelijko! glad you found it valuable!
You are awesome! Thank you for your videos!
Thanks Dimitris, thanks for watching!
great video, thank you very much, kind sir :)
Thanks for watching, glad you found it valuable!
most make-sense explanation of lifetimes i've seen.
fantastic, thank you! 😎
I really like the sound of the sped up keystrokes 🙂 Ok, I will now try to learn about Rust too..
Hah yeah when I first started speeding up the typing parts, my first instinct was to silence the audio, then I realized it sounds nice in a weird way...
I think I found my new favorite Rust channel.
Nice, very happy to have you onboard!
Awesome video, really gave me clarity on both core concepts that I was in proverbly desperate need of. I wish Borrowing and Lifetimes were denoted a bit simpler in the code though, like just seeing an ampersand & is bonkers weird for a newbie and denoting lifetimes with both generics arrows and a single quote? Like, that's weird, and feels obtuse no matter how you slice and dice it (or borrow and mutate it).