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Rust is a great language if you use for what was intended, system programming and as safe substitute of C and C++. But it's not the answer of everything, to me

Rust is a great language if you use for what was intended, system programming and as safe substitute of C and C++. But it's not the answer of everything, to me it's nowadays abused in a lot of projects, there are instances of project where using Rust not only doesn't make a lot of sense but also can be slower than another languages, there are cases where Go is better, other where Node.js is better, other where Python is better, other where Java is better, etc. To me the Rust community seems to want to argue that everything should be rewritten in Rust, just because Rust solves every problem, while it's not.

s_y_n_t_a_x 7y ago
One major reason for the recent explosion is it's first class WASM support, especially since it doesn't need a GC. It just has language features that make sense for the web, which is a huge sector. (parallelism, memory safety, speed, JS interop)
Ididntdothis 7y ago
I think that’s ok. It takes a while to figure out where a language is ok and where it’s maybe not ok. Also by doing stuff it may not be perfectly suited for right now there is an incentive for improving things.
MadWombat 7y ago
OK, I will bite. If I had to come up with a case where Python is better than Rust, I would say with rapid prototyping and scientific computing. If you just want to try a few things out, python has faster development cycle and if you want to do some super clever math python has better library support. With a bit more mind stretching, I can make a case for Go with a bit more mind stretching. If you want to write a massively parallel network server of some sort you might be better off with Go, especially if you want to use protobufs and grpc. But what would be the case for Node and Java?
- terminaljunkid 7y ago
  Ecosystem.. I don't know about node. But there's whole lot of java code and libraries out there. Otherwise why would people build other languages for the JVM? Ease of writing; Most of code is okay having a GC. But time to produce working code (not necessarily 100% correct code) is important. Rust is created for low level stuff. It is wrong to expect web backend programmers to deal with ownership, stack-vs-heap and all.
  - MadWombat 7y ago
    > It is wrong to expect web backend programmers to deal with ownership, stack-vs-heap and all. I am a web backend programmer. I respectfully disagree. I would much rather deal with ownerhip and related issues than deal with dynamic typing fallout. Unfortunately, I am stuck in Python land for some foreseeable future. > But there's whole lot of java code and libraries out there. That is true about every other popular language. Rust might not have the ecosystem, being a lot younger, but why would anyone pick Java out of all the other options? As far as I can tell, the only two reasons people continue coding in Java are "We have an existing Java ecosystem, it is easier to continue doing what we have been doing than to switch" and "Java is what we know best and it is easier to use Java than to learn new technology stack".
    - sweeneyrod 7y ago
      > I would much rather deal with ownerhip and related issues than deal with dynamic typing fallout. Those two things aren't connected. You can avoid both of them by using one of the many statically typed languages with a GC. It might be the case that Rust has other advantages over those languages that make power-assisted manual memory management a cost worth bearing, but it is still a cost. The amount of successful web backends written in Python/Ruby shows that performance demands on a typical web app are nowhere near high enough to justify doing away with the GC.
    - bcrosby95 7y ago
      Here's why we use Java: 1. It performs well - we're a small company, so hardware costs matter to us. Its a similar performance class as Go and C# - if you want to go faster, you likely have to use Rust, C, or C++. 2. As said, the ecosystem is huge. If you need to do something, there's probably a library or tool for it. If you have a problem with one of their libs, someone else had the problem too. Unless your business is consulting, spending your time going down paths no one else has gone down just so you can use a shiny new language is a waste of resources. 3. The language isn't full of too many concepts. This makes it easier to get people up to speed with it if they're unfamiliar. I like Rust for some personal projects, but lots of the complexity of the language is completely pointless for most of what we do at my company. 4. The JVM is great. 5. We already know it. Even ignoring #5, our priority of languages is probably C#/Java, then Go. Java is a meh language. And I feel like the annotation soup only makes it worse: it makes Java both verbose and magical, a truly shitty combination. But the ecosystem is awesome. The performance is good. The JVM is great. With .NET Core, it might make sense to look at C#. But the language is fairly similar to Java anyways. Switching for switching's sake seems pointless. And Microsoft only relatively recently started officially supporting Linux, so I would be wary of using it for greenfield, much less switching our existing company. Kotlin is a decent contender here too. But it's not that widespread as a backend language, at least not yet. If I could pick any language, I would choose Clojure because it benefits somewhat from Java's ecosystem and is (IMHO) the best JVM language. Immutability is killer, and I find dynamic typing with specs a good middleground between purely dynamic and purely static languages. But Clojure makes things pretty difficult when it comes to the hiring end of things and developer familiarity. If I worked at a greenfield company solving the same problems I do today, Java would probably still be my first choice.
- jayd16 7y ago
  Can Rust do things like heap compaction? You could do it by hand I guess but its not exactly trivial. There's probably a whole class of problems the GC still excels at. JVM tooling is also pretty nice. Can you trivially get deep app metrics from any Rust program?
  - steveklabnik 7y ago
    I think you're asking rhetorically, but just in case: 1. Rust-the-language doesn't know anything about allocations, so strictly speaking, it cannot. Furthermore, without a GC, it's unclear how it could in the first place, given that a compaction would invalidate all pointers to that memory. 2. Certainly not to the same degree as the JVM, given that there's nothing inherently to inspect, like there is in languages with a runtime. You can instrument your own application, but that does mean doing the work yourself, and you only get as good of results as you put in in the first place.
    - zozbot234 7y ago
      > Rust-the-language doesn't know anything about allocations AIUI, Rust knows more about allocations than it should, since it's still limited to a single global allocator, and Box<> (which relies on that global allocator) is implemented via compiler magic and cannot be supplemented by equivalent library code. If Rust supported "pluggable" allocators in some fashion, fancy features (including heap compaction, although I find that a bit dubious TBH) might become easier to implement.
      - Ar-Curunir 7y ago
        `std` data structures that are generic over type of allocator are in the works.
      - shepmaster 7y ago
        > If Rust supported "pluggable" allocators in some fashion It's coming, but it's still unstable and being actively developed - https://github.com/rust-lang/rust/issues/32838 https://github.com/rust-lang/rust/issues/32838
- ggregoire 7y ago
  > If I had to come up with a case where Python is better than Rust, I would say with rapid prototyping and scientific computing. Scripting? I'm not gonna write a 50 LOC single-use script in Rust.
  - estebank 7y ago
    I've found that a lot of scripts end up not being single use. In my case they usually do end up rewritten in Rust, with the benefits of having a proper --help command from the bother. Once you know enough Rust the obtuse parts of the language that must exist to cater for the performance critical crowd cease to be a problem.
  - oconnor663 7y ago
    I do write a lot of Python and Bash scripts, even in my Rust projects. They're perfect for gluing together a build. But I'd add that as soon as I want an external dependency (often a more featureful command line flag parsing library), I usually RIIR.
- christiansakai 7y ago
  For massively parallel even with async, I still think Go is better than NodeJS. I still don't know how to do bounded parallelism in NodeJS but really easy in Go.
  - lostcolony 7y ago
    https://github.com/caolan/async/blob/master/lib/internal/eachOfLimit.js https://github.com/caolan/async/blob/master/lib/internal/eac... - this is the code the async Node lib uses for every "(X)Limit" function to limit the number run at once.
steveklabnik 7y ago
The key is in another comment on this thread: > Lots of these things that look like syntax problems are in fact design problems surfaced by the compiler. A lot of people are finding value in the rules Rust provides. This is irrespective of domain. The strict compiler helps you refactor code in ways that less strict languages don't. You still can do it, of course, you just have a lot less help. The trick is, is the initial hit in productivity worth it, until you get up to speed? That said, of course everything doesn't need to be in Rust. But there's a reason it's finding broader appeal than purely systems stuff.
- sdegutis 7y ago
  I think this is misplaced causation. Don’t discount the fact that a significant number of programmers just like novelty and like Rust because it’s new in the same way Haskell is new to a Java dev. That said, Rust’s domain does seem wider than just systems programming. It has the right abstractions to be suitable for (edit: some) higher level things like web apps. Personally Rust is turning into what I was assuming and hoping Go was going to turn into back in 2010: a static language that does most of what we all used dynamic languages for, without too much extra difficulty. (That is, after you get used to the borrow checker’s rules.)
  - shepmaster 7y ago
    > because it’s new in the same way Haskell is new to a Java dev Do you have any hypotheses about why we don't see as much publicity for Haskell then?
    - sdegutis 7y ago
      Hey nice to see you here, your SO posts have tremendously helped me learn Rust. I think Haskell is just too abstract for most of us. I love Rust traits and see how it directly came from Haskell but I couldn’t learn Haskell even after like 3 serious tries. Maybe a good portion of the problem is in the documentation and not the language? That said, the extremist purity is simply impractical compared to Rust which gets 90% of the way there without forcing all the architectural dances Haskell does. Just my opinion.
sambe 7y ago
I don't recall seeing the community arguing strongly for re-writes. I see people who want to do rewrites for fun/education. For example, just because they love the language and prefer to work in it. In some cases people make the case for re-writing sensitive libraries in Rust, but I think a) they are not in general arguing confrontationally; b) they tend to have a point technically speaking. The missing piece is whether it makes sense long-term, with different pools of potential contributors etc.
Brave-Steak 7y ago
> To me the Rust community seems to want to argue that everything should be rewritten in Rust I haven't seen this. At most, I've seen the push for rewriting important libraries where security is a core issue in Rust. I don't blame them. I'm tired of C/C++ being used everywhere because of performance, leading to the current-day situation of so much fundamentally unsafe code running the world.
- CJefferson 7y ago
  I'm involved in a couple of github projects where we have had drive-by "hey, rewrite your project in Rust" PRs. Obviously not official or anything, but never seen anything like that for any other language.
  - mrec 7y ago
    Oh, back when Java first came out, Sun themselves were pushing this ("Rewrite it in Java!") line in spades. The hype train was unbelievable back then.
  - runevault 7y ago
    I feel like those are actually trolls. I don't remember the last time I saw someone serious about rust doing those types of silly stunts.
- ncmncm 7y ago
  There is no such language as C/C++. You and I are tired of C being used where using a more powerful, safer language would also be faster. Rust could be that language, but C++ is another, and much more likely to still be known in ten years.
  - Brave-Steak 7y ago
    / = or As in C or C++. I didn't mean it as its own language. And C++ has plenty of issues where I'd consider it equally unsafe. Unless you're a god tier programmer, and even then, it's impossible to write safe code without insane amounts of effort that can't be expected in most projects.
spamizbad 7y ago
I find it comforting that the Rust community is casting a wide net, even if it’s not always the best fit. It’s something I always enjoy about working with Python. There are some platforms and ecosystems that pour 90% of the effort into a handful of popular niches, but once you leave that comfort zone you’re on your own. Elixir can feel like that; Ruby/Rails too back in the day.

s_y_n_t_a_x 7y ago

One major reason for the recent explosion is it's first class WASM support, especially since it doesn't need a GC. It just has language features that make sense for the web, which is a huge sector. (parallelism, memory safety, speed, JS interop)

Ididntdothis 7y ago

I think that’s ok. It takes a while to figure out where a language is ok and where it’s maybe not ok. Also by doing stuff it may not be perfectly suited for right now there is an incentive for improving things.

MadWombat 7y ago

OK, I will bite. If I had to come up with a case where Python is better than Rust, I would say with rapid prototyping and scientific computing. If you just want to try a few things out, python has faster development cycle and if you want to do some super clever math python has better library support. With a bit more mind stretching, I can make a case for Go with a bit more mind stretching. If you want to write a massively parallel network server of some sort you might be better off with Go, especially if you want to use protobufs and grpc. But what would be the case for Node and Java?

terminaljunkid 7y ago
Ecosystem.. I don't know about node. But there's whole lot of java code and libraries out there. Otherwise why would people build other languages for the JVM? Ease of writing; Most of code is okay having a GC. But time to produce working code (not necessarily 100% correct code) is important. Rust is created for low level stuff. It is wrong to expect web backend programmers to deal with ownership, stack-vs-heap and all.
- MadWombat 7y ago
  > It is wrong to expect web backend programmers to deal with ownership, stack-vs-heap and all. I am a web backend programmer. I respectfully disagree. I would much rather deal with ownerhip and related issues than deal with dynamic typing fallout. Unfortunately, I am stuck in Python land for some foreseeable future. > But there's whole lot of java code and libraries out there. That is true about every other popular language. Rust might not have the ecosystem, being a lot younger, but why would anyone pick Java out of all the other options? As far as I can tell, the only two reasons people continue coding in Java are "We have an existing Java ecosystem, it is easier to continue doing what we have been doing than to switch" and "Java is what we know best and it is easier to use Java than to learn new technology stack".
  - sweeneyrod 7y ago
    > I would much rather deal with ownerhip and related issues than deal with dynamic typing fallout. Those two things aren't connected. You can avoid both of them by using one of the many statically typed languages with a GC. It might be the case that Rust has other advantages over those languages that make power-assisted manual memory management a cost worth bearing, but it is still a cost. The amount of successful web backends written in Python/Ruby shows that performance demands on a typical web app are nowhere near high enough to justify doing away with the GC.
  - bcrosby95 7y ago
    Here's why we use Java: 1. It performs well - we're a small company, so hardware costs matter to us. Its a similar performance class as Go and C# - if you want to go faster, you likely have to use Rust, C, or C++. 2. As said, the ecosystem is huge. If you need to do something, there's probably a library or tool for it. If you have a problem with one of their libs, someone else had the problem too. Unless your business is consulting, spending your time going down paths no one else has gone down just so you can use a shiny new language is a waste of resources. 3. The language isn't full of too many concepts. This makes it easier to get people up to speed with it if they're unfamiliar. I like Rust for some personal projects, but lots of the complexity of the language is completely pointless for most of what we do at my company. 4. The JVM is great. 5. We already know it. Even ignoring #5, our priority of languages is probably C#/Java, then Go. Java is a meh language. And I feel like the annotation soup only makes it worse: it makes Java both verbose and magical, a truly shitty combination. But the ecosystem is awesome. The performance is good. The JVM is great. With .NET Core, it might make sense to look at C#. But the language is fairly similar to Java anyways. Switching for switching's sake seems pointless. And Microsoft only relatively recently started officially supporting Linux, so I would be wary of using it for greenfield, much less switching our existing company. Kotlin is a decent contender here too. But it's not that widespread as a backend language, at least not yet. If I could pick any language, I would choose Clojure because it benefits somewhat from Java's ecosystem and is (IMHO) the best JVM language. Immutability is killer, and I find dynamic typing with specs a good middleground between purely dynamic and purely static languages. But Clojure makes things pretty difficult when it comes to the hiring end of things and developer familiarity. If I worked at a greenfield company solving the same problems I do today, Java would probably still be my first choice.
jayd16 7y ago
Can Rust do things like heap compaction? You could do it by hand I guess but its not exactly trivial. There's probably a whole class of problems the GC still excels at. JVM tooling is also pretty nice. Can you trivially get deep app metrics from any Rust program?
- steveklabnik 7y ago
  I think you're asking rhetorically, but just in case: 1. Rust-the-language doesn't know anything about allocations, so strictly speaking, it cannot. Furthermore, without a GC, it's unclear how it could in the first place, given that a compaction would invalidate all pointers to that memory. 2. Certainly not to the same degree as the JVM, given that there's nothing inherently to inspect, like there is in languages with a runtime. You can instrument your own application, but that does mean doing the work yourself, and you only get as good of results as you put in in the first place.
  - zozbot234 7y ago
    > Rust-the-language doesn't know anything about allocations AIUI, Rust knows more about allocations than it should, since it's still limited to a single global allocator, and Box<> (which relies on that global allocator) is implemented via compiler magic and cannot be supplemented by equivalent library code. If Rust supported "pluggable" allocators in some fashion, fancy features (including heap compaction, although I find that a bit dubious TBH) might become easier to implement.
    - Ar-Curunir 7y ago
      `std` data structures that are generic over type of allocator are in the works.
    - shepmaster 7y ago
      > If Rust supported "pluggable" allocators in some fashion It's coming, but it's still unstable and being actively developed - https://github.com/rust-lang/rust/issues/32838 https://github.com/rust-lang/rust/issues/32838
ggregoire 7y ago
> If I had to come up with a case where Python is better than Rust, I would say with rapid prototyping and scientific computing. Scripting? I'm not gonna write a 50 LOC single-use script in Rust.
- estebank 7y ago
  I've found that a lot of scripts end up not being single use. In my case they usually do end up rewritten in Rust, with the benefits of having a proper --help command from the bother. Once you know enough Rust the obtuse parts of the language that must exist to cater for the performance critical crowd cease to be a problem.
- oconnor663 7y ago
  I do write a lot of Python and Bash scripts, even in my Rust projects. They're perfect for gluing together a build. But I'd add that as soon as I want an external dependency (often a more featureful command line flag parsing library), I usually RIIR.
christiansakai 7y ago
For massively parallel even with async, I still think Go is better than NodeJS. I still don't know how to do bounded parallelism in NodeJS but really easy in Go.
- lostcolony 7y ago
  https://github.com/caolan/async/blob/master/lib/internal/eachOfLimit.js https://github.com/caolan/async/blob/master/lib/internal/eac... - this is the code the async Node lib uses for every "(X)Limit" function to limit the number run at once.

steveklabnik 7y ago

The key is in another comment on this thread: > Lots of these things that look like syntax problems are in fact design problems surfaced by the compiler. A lot of people are finding value in the rules Rust provides. This is irrespective of domain. The strict compiler helps you refactor code in ways that less strict languages don't. You still can do it, of course, you just have a lot less help. The trick is, is the initial hit in productivity worth it, until you get up to speed? That said, of course everything doesn't need to be in Rust. But there's a reason it's finding broader appeal than purely systems stuff.

sdegutis 7y ago
I think this is misplaced causation. Don’t discount the fact that a significant number of programmers just like novelty and like Rust because it’s new in the same way Haskell is new to a Java dev. That said, Rust’s domain does seem wider than just systems programming. It has the right abstractions to be suitable for (edit: some) higher level things like web apps. Personally Rust is turning into what I was assuming and hoping Go was going to turn into back in 2010: a static language that does most of what we all used dynamic languages for, without too much extra difficulty. (That is, after you get used to the borrow checker’s rules.)
- shepmaster 7y ago
  > because it’s new in the same way Haskell is new to a Java dev Do you have any hypotheses about why we don't see as much publicity for Haskell then?
  - sdegutis 7y ago
    Hey nice to see you here, your SO posts have tremendously helped me learn Rust. I think Haskell is just too abstract for most of us. I love Rust traits and see how it directly came from Haskell but I couldn’t learn Haskell even after like 3 serious tries. Maybe a good portion of the problem is in the documentation and not the language? That said, the extremist purity is simply impractical compared to Rust which gets 90% of the way there without forcing all the architectural dances Haskell does. Just my opinion.

sambe 7y ago

I don't recall seeing the community arguing strongly for re-writes. I see people who want to do rewrites for fun/education. For example, just because they love the language and prefer to work in it. In some cases people make the case for re-writing sensitive libraries in Rust, but I think a) they are not in general arguing confrontationally; b) they tend to have a point technically speaking. The missing piece is whether it makes sense long-term, with different pools of potential contributors etc.

Brave-Steak 7y ago

> To me the Rust community seems to want to argue that everything should be rewritten in Rust I haven't seen this. At most, I've seen the push for rewriting important libraries where security is a core issue in Rust. I don't blame them. I'm tired of C/C++ being used everywhere because of performance, leading to the current-day situation of so much fundamentally unsafe code running the world.

CJefferson 7y ago
I'm involved in a couple of github projects where we have had drive-by "hey, rewrite your project in Rust" PRs. Obviously not official or anything, but never seen anything like that for any other language.
- mrec 7y ago
  Oh, back when Java first came out, Sun themselves were pushing this ("Rewrite it in Java!") line in spades. The hype train was unbelievable back then.
- runevault 7y ago
  I feel like those are actually trolls. I don't remember the last time I saw someone serious about rust doing those types of silly stunts.
ncmncm 7y ago
There is no such language as C/C++. You and I are tired of C being used where using a more powerful, safer language would also be faster. Rust could be that language, but C++ is another, and much more likely to still be known in ten years.
- Brave-Steak 7y ago
  / = or As in C or C++. I didn't mean it as its own language. And C++ has plenty of issues where I'd consider it equally unsafe. Unless you're a god tier programmer, and even then, it's impossible to write safe code without insane amounts of effort that can't be expected in most projects.

spamizbad 7y ago

I find it comforting that the Rust community is casting a wide net, even if it’s not always the best fit. It’s something I always enjoy about working with Python. There are some platforms and ecosystems that pour 90% of the effort into a handful of popular niches, but once you leave that comfort zone you’re on your own. Elixir can feel like that; Ruby/Rails too back in the day.