Using Rust at a startup: A cautionary tale

I&#x27;m not sure I agree with the article&#x27;s premises. Rust can be difficult, yes, but it can also heighten developer productivity above other languages. In Go, I&#x27;d have to worry about whether I checked for exceptions via `if err != nil` everywhere, while with Rust, I can depend on the compiler telling me if I haven&#x27;t done so exhaustively, via the Result type. Same for having algebraic data types or, well, generics in general.<p>I will also push back on other commentors here saying Rust is not good for web apps and APIs, and I have found that to be the opposite of true. I read Zero To Production In Rust [0] (a great book by the way, all about creating a web API with actix-web and Postgres) and deployed an API that has not gone down a single time since deploying near the beginning of this year. It&#x27;s as ergonomic as (and sometimes even more so than) any NodeJS or Go API I&#x27;ve made (as even though Rust doesn&#x27;t have function overloading, actix-web and others have some macro magic they do behind the scenes to make it appear as if it does), and there were very few times I had to contend with the borrow checker. If there had been and if I were really going for speed, I would also have cloned everywhere that was needed.<p>When I write something in Rust and it compiles, I can depend on it to work, and to continue working. At the end of the day, use the tool that makes sense for your business, but I don&#x27;t think Rust was necessarily a bad choice based on my personal experience with it.<p>[0] <a href="https:&#x2F;&#x2F;www.zero2prod.com&#x2F;" rel="nofollow">https:&#x2F;&#x2F;www.zero2prod.com&#x2F;</a>

&gt; <i>With Rust, though, one needs to learn entirely new ideas — things like lifetimes, ownership, and the borrow checker.</i><p>This is really the main reason not to use Rust when you need to move fast: if you don&#x27;t know the language yet, it will take you time to learn it. But that&#x27;s true of <i>any</i> language. You probably shouldn&#x27;t do your startup in Java, either, if your team isn&#x27;t familiar with it.<p>Yes, Rust&#x27;s learning curve is steeper than many other languages, but still... if you&#x27;re an early-stage startup and you need to move fast, <i>write in a language that you and your team already knows</i>.

&gt; We hired a ton of people during my time at this company, but only about two or three of the 60+ people that joined the engineering team had previous experience with Rust. This was not for want of trying to find Rust devs — they just aren’t out there.<p>As an experienced Rust dev, I had the opposite problem. I looked for a good Rust job, but couldn&#x27;t find one. Took an Elixir job instead.<p>I also don&#x27;t get the complaint about lack of productivity. I&#x27;ve worked in a dozen languages, and Rust is still the most productive language for me by far. I feel like they&#x27;re speaking from inexperience here. I&#x27;m slow whenever I start a new language too, and Rust was no exception. Keep at it, however, and it&#x27;ll pay off in the long run.

&gt; My primary experience from Rust comes from working with it for a little more than 2 years at a previous startup. This project was a cloud-based SaaS product that is, more-or-less, a conventional CRUD app<p>I think this should be at the top of the post. Rust seems like an obvious bad choice for this. For something not performance-sensitive that doesn&#x27;t require most of Rust&#x27;s power just use languages&#x2F;frameworks that are made for this kind of thing. Of course you can do this with Rust, but you&#x27;re probably picking the wrong tool for the job. The Rust ecosystem around building typical webservices isn&#x27;t nearly as good as it is for other languages, and the benefit you get from Rust&#x27;s safety and performance is worth less than the iteration speed you gain from the standard Node&#x2F;Python&#x2F;etc approach.

I use Rust at a startup, and it&#x27;s been great.<p>But I&#x27;ve used Rust mostly for performance-critical CLI tools, or highly specialized servers. Typically, these have a narrowly defined job that must be done reliably and efficiently. Rust shines at this. These tools run reliably with almost no changes, often for years at a time.<p>But I have learned that it&#x27;s often less useful putting policy and frequently-changed business logic in Rust. That kind of code is often accessible to more developers in a strongly-typed scripting language.

Interesting. By contrast, I wish I had used less Python and more Rust for my company&#x27;s product because Rust is considerably more productive. We were building gRPC and web services.<p>I just haven&#x27;t found it to be the case that developers have a very hard time learning it, but we haven&#x27;t grown to the point where that would maybe be the case. We also lean heavily into microservices so &quot;oh there&#x27;s no library in Rust but there&#x27;s one in Python&quot; is low cost, we can just write a service in Python.

&gt; Rust was used primarily because a couple of the founders of the company were Rust experts<p>It&#x27;s remarkable how significantly the first few months of a project impact the first few years of a company. How quickly casual &amp; spontaneous decisions, largely based on convenience and familiarity, ossify into legacy drag.

I&#x27;ve noticed that Rust is in an interesting spot - it has a lot of overlapping appeal with various groups.<p>- C&#x2F;C++ developers like it as an alternative for low level languages<p>- Functional programmers like it because of it&#x27;s functional features<p>- &quot;Cargo Culters&quot; &#x2F; &quot;Hot Language&quot; &#x2F; &quot;Flavor of the Month&quot; followers like it, as it&#x27;s in vogue at the moment (this is the crowd that has likely shifted from various web&#x2F;API scripting languages over the last decade - (php|ruby|python) -&gt; nodejs -&gt; rust)<p>However, as the article alludes to, for the third crowd, Rust is just likely not a great fit (even if it has a lot of neat features and introduces some great concepts others may not stumble on of their own accord) when your implementation doesn&#x27;t do much beyond web dev&#x2F;API&#x2F;scripting purposes.

While I respect the author&#x27;s anecdote, this doesn&#x27;t match my experience. I&#x27;ve been programming for 20+ years across a wide array of languages and I&#x27;m by far the most productive in Rust.<p>With a competent teacher, experienced devs should be able to pick up on the memory model pretty quickly, and that is really the only initial blocker to productivity. After that a dev can essentially write procedural code if they want, like other common languages, while refining their thinking and practices towards idiomatic Rust.

Isn’t it about time for a language with a runtime with an HTTP server and SQL database? There’s literally millions of us writing basically the same code over and over again: listen on port 80, parse and transform text more times than necessary to make a SQL call to then parse and transform the returned rows into text more times than necessary to return some JSON or HTML.<p>The wasted clock cycles and developer hours more than makes up for the slow down in productivity rates we’ve seen across advanced economies lately!

&gt; Rust is awesome, for certain things.<p>&gt; This project was a cloud-based SaaS product that is, more-or-less, a conventional CRUD app: it is a set of microservices that provide a REST and gRPC API endpoint in front of a database, as well as some other back-end microservices<p>Of course.<p>Use Java&#x2F;Kotlin or Node.js&#x2F;Typescript or Go or Python for your basic web services.<p>Easy test: Would you at least seriously <i>consider</i> using C&#x2F;C++ for it? Only then should you use Rust.

I didn&#x27;t see it here, but one of the points that doesn&#x27;t seem to be expanded on too well is that despite liking Rust, I wouldn&#x27;t use it for a basic web server in a startup environment either, mainly because the whole environment around web stuff is too immature in my experience.<p>Ruby on Rails certainly isn&#x27;t perfect, but it&#x27;s a highly battle-tested web framework. It&#x27;s been so widely used for so long that you can have high confidence that you won&#x27;t run into any bugs that will require digging into the guts of it. You can write code against it and be highly confident that any bugs or misbehaviors are in your code, with difficulty of finding and fixing dependent only on how good the code you&#x27;ve written is.<p>With Rust, I don&#x27;t think that&#x27;s the case. The DB and web server related libs just don&#x27;t seem to have that much manpower behind them, and haven&#x27;t had big complex services built on them in production for years. If you want to do anything mildly complex, there&#x27;s a good chance you&#x27;ll have to dig into the guts of these to figure out what&#x27;s really happening or to resolve some weird bug or add a feature. That&#x27;ll require a lot of skill, even if the code you&#x27;re actually writing is mostly straightforward.

The arguing about Rust seems to miss that Rust protects against more than just security bugs.<p>If you&#x27;ve ever generated some object out of some factory and then tossed it on a list of things and then gone back to generate a new object out of the factory and found that the first object you put on the list got scribbled over because you forgot to clone it, then that&#x27;s a category of bugs that rust entirely prevents.<p>And I thought I was pretty good about reasoning about data ownership in other languages, but the borrow checker is teaching me how to be a lot more careful.

This matches my experience.<p>I have been doing compiler development in C++ for about 10 years, lisp before that and a bit of python more recently.<p>We could not figure out how to be productive in Rust after starting a greenfield project and sticking to it for a month.<p>Luckily this was not a project which requires incremental updates, we were on the verge of rewriting it in C++.

&quot;I would much rather have my team sink time into debugging the occasional memory leak or type error for code written in, say, Python or Go, than have everyone on the team suffer a 4x productivity hit for using a language designed to avoid these problems entirely.&quot;<p>I&#x27;m not sure if I agree with this. In fact, I&#x27;m pretty sure that I don&#x27;t. These &quot;occasional&quot; nuisances become big blockers after a while and not only decrease productivity but hurt customer goodwill as well when they&#x27;re not discovered in time.

There&#x27;s a reason why we see so many articles like &quot;we rewrote x in rust.&quot; Rust makes sense when you&#x27;ve scaled to the point that you&#x27;re seriously considering performance. Sure, starting with rust can potentially save you time, money, and refactoring down the line but only after you&#x27;ve reached a point that few startups ever hit. Otherwise you&#x27;re limiting yourself with slow development times (compared to, say, Python) and difficulty hiring for very little benefit. I&#x27;m sure this startup&#x27;s founders love rust (and so do I), but ultimately you need to prioritize the company first and that probably means using the most popular, boring tech stack imaginable in the beginning. The more you deviate from that, the harder the early days will be. It&#x27;s far too easy to be swayed by exciting tech and forget that all that really matters is that you solve someone&#x27;s problem.

I&#x27;ve seen a pretty clear difference in success with less popular technologies based more on management philosophy and culture than the technologies themselves. Management seeing individual developers as fungible—&quot;lack of fungibility in the engineering team can be a real liability&quot;—is a massive red flag in this regard. I am not surprised to hear Rust didn&#x27;t work out in an environment like that!

While the author&#x27;s anecdotal evidence is coherent, it&#x27;s not enough to establish causation. Especially if the measure of productivity is feelings of sluggishness.<p>Rust or not, there&#x27;s an argument to be made for statically typed languages improving productivity over the long run [0].<p>All development can feel sluggish depending on the work hours, estimates, business timelines, engineering skills, and the task at hand.<p>Programming languages are common targets because - we use them so much - there are so many - and all developers, at some point, must choose to dedicate their time to one over the others.<p>Finally, productivity itself is only one performance characteristic. To focus only on that (without even a good definition of effect or measure) makes content precisely what the author claims to avoid; flame bait.<p>[0] - <a href="https:&#x2F;&#x2F;www.researchgate.net&#x2F;publication&#x2F;338162224_A_Study_of_Programming_Languages_and_Their_Bug_Resolution_Characteristics" rel="nofollow">https:&#x2F;&#x2F;www.researchgate.net&#x2F;publication&#x2F;338162224_A_Study_o...</a>

As usual, very sad to see how little C# is mentioned as an alternative, having very robust, easy to use and performant stack of standard and third-party libraries for building the exact scenario outlined in the article.<p>Especially that is has first-class support for gRPC, runs on every cloud&#x2F;on-prem host you can think of and doesn&#x27;t force you to go out of your way to get most performance out of your implementation. People should not be mentioning Java first as a GC&#x2F;JIT-based language for cloud given how competitive C# stack is and how much more you get straight out of the box.

I&#x27;m in the middle of a rewrite of my finance analytics library in Rust. I chose it for all the compelling reasons: speed, safety and a great package manager.<p>About 2 weeks in, I hit a blocker, where the most performance critical layer was running 30x slower than C#. It&#x27;s two weeks since then, and I&#x27;m still blocked. Experienced programmers on the language Discord and Reddit have been stumped as well, and I get the impression this is what one should expect from an immature ecosystem, but also makes me fear that it will never actually catch on.<p>Point is, I think even the selling point of speed is inappropriate.

<i>&gt; I’ve worked in dozens of languages in my career, and with few exceptions most modern, procedural languages (C++, Go, Python, Java, etc.) all very similar in terms of their basic concepts. Each language has its differences but usually it’s a matter of learning a few key patterns that differ across languages and then one can be productive pretty quickly. With Rust, though, one needs to learn entirely new ideas</i><p>I&#x27;d argue C++ is not anywhere easier, if you are using its features or need to analyze the code that does. It won&#x27;t be anywhere quick.

&gt; Rust makes roughing out new features very hard.<p>&gt; I don’t know about anyone else, but at least for me, when I’m building a new feature I usually don’t have all the data types, APIs, and other fine details worked out up front. I’m often just farting out code trying to get some basic idea working and checking whether my assumptions about how things should work are more-or-less correct. Doing this in, say, Python is extremely easy, because you can play fast and loose with things like typing and not worry if certain code paths are broken while you rough out your idea. You can go back later and make it all tidy and fix all the type errors and write all the tests.<p>&gt; In Rust, this kind of “draft coding” is very difficult, because the compiler can and will complain about every goddamn thing that does not pass type and lifetime checking — as it is explicitly designed to do. This makes perfect sense when you need to build your final, production-ready implementation, but absolutely sucks when you’re trying to cruft something together to test an idea or get a basic foundation in place. The unimplemented! macro is helpful to a point, but still requires that everything typechecks up and down the stack before you can even compile.<p>This rings so true for me. I could &quot;mock up&quot; entire apps using interfaces in Java, without having to actually write impl code. I could be sloppy as hell around the edges, but that didn&#x27;t matter, because I could get the large design right without the compiler screaming.<p>In Rust, there is the chasm between no code and anything that works, feels so draggy.

I&#x27;d say the author brought a good point of why you should use Rust even for a CRUD app. (and yeah, I am a Rust fanatic and quite biased too). But hear me out.<p>&gt; Over time, we grew the team considerably (increasing the engineering headcount by nearly 10x), and the size and complexity of the codebase grew considerably as well.<p>At this point, Rust is providing security and protection from technical debt. You have lots of new comers to the company&#x2F;project and each one of them is adding or changing something. Developers being normal human beings have the tendency not to read documentation, old code or discuss with 100 engineers before building something.<p>Rust forces that on them, to a certain degree. Sure, you can move faster without Rust for now; but you&#x27;ll pay the price later on. I am working on a company where we are doing microservices both in Rust and TypeScript. It&#x27;s faster to get the job done in TypeScript; however, the cost is the maintenance later. The TS microservices breaks easily, regress much faster when someone modifies them, and are prone to invisible bugs. Rust is more solid in that front.<p>But in a world where speed of delivery and delivery itself (just deliver and deal with it later), Rust will definitively not shine. This is kicking the problem down to somebody else.<p>Another point: Because of that, Rust libraries are usually pretty solid. Comparing to the untangled mess in NPM, Rust will break down much less frequently.

&gt; What really bites is when you need to change the type signature of a load-bearing &gt; interface and find yourself spending hours changing every place where the type is &gt; used only to see if your initial stab at something is feasible<p>Editor&#x2F;IDE should be able to do this in a few seconds.

&gt; With Rust, though, one needs to learn entirely new ideas — things like lifetimes, ownership, and the borrow checker.<p>Those three things are actually just different facets of the same thing: ownership. The bad news is that you must learn Rust&#x27;s ownership model to use Rust idiomatically. The good news is that you can do a lot without learning Rust ownership model at all. Just clone all your values. Not advisable for production code, but great for getting over the ownership model hump.

&gt; This project was a cloud-based SaaS product that is, more-or-less, a conventional CRUD app<p>I would love to hear what tech stack (or stacks) the HN community thinks currently allows a small team to move fastest for this type of product.

&quot;Rust has made the decision that safety is more important than developer productivity. This is the right tradeoff to make in many situations — like building code in an OS kernel, or for memory-constrained embedded systems — but I don’t think it’s the right tradeoff in all cases, especially not in startups where velocity is crucial&quot;<p>Great point

Just once I wish I could force a Rust person to use either Ada, or even an Oberon-2 derivative that spits out C code and which compiles in a flash. Then compare the experience...

Are there languages that copy Rust&#x27;s type system and compiler ergonomics without the memory safety?<p>I feel like 90% of my struggles with Rust in the real world have to do with the borrow checker. The two pieces don&#x27;t feel related enough to me that they need to be interlinked.

I am building modelbox right now - <a href="https:&#x2F;&#x2F;github.com&#x2F;tensorland&#x2F;modelbox" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;tensorland&#x2F;modelbox</a> I began building this in Rust while also learning the language. It became quickly very complex as I started introducing streams in async traits. I think in a few years things will get a lot better as more people use Rust for building web services, but I had to go back to Go to be more productive and ship this thing out. I loved how the compiler was forcing me to think harder about life times and such.

I personally have a startup and what I think works well is use TypeScript for almost everything, but Rust for anything that has to be fast and&#x2F;or needs more code safety due to complexity.

I hope more people looking into statically typed languages like Rust also take a look at Nim, as it seems to be striking a good balance between performance and developer productivity.

,,Over time, we grew the team considerably (increasing the engineering headcount by nearly 10x), and the size and complexity of the codebase grew considerably as well.&#x27;&#x27;<p>This sounds just like all other projects that don&#x27;t keep the code professional.<p>The author complains a lot about the quality of the Rust libraries and documentation, but I bet that their code base and documentation and especially testing is worse.<p>Still, I agree that Rust is not ready for a startup where the requirements change often.

&gt; As mentioned above, the service we were building was a fairly straightforward CRUD app. The expected load on this service was going to be on the order no more than a few queries per second, max, through the lifetime of this particular system.<p>Naturally, there is a reason people opt for higher level languages like Ruby&#x2F;Python or at least Go or Java&#x2F;Kotlin to write apps like this.

I really, really, really, don&#x27;t understand why people want to use Rust for CRUD&#x2F;web stuff. <i>Every</i> GC language is better than Rust for CRUD&#x2F;web when you are in the less than 10,000 users phase.<p>I understand why <i>Rust</i> is trying to shove its way into the CRUD&#x2F;web space--that&#x27;s where all the programming is. I just don&#x27;t understand the converse.

I feel that this is a click bait to attract employees. The writer links to his startup on his profile (which Medium shows right next to the article), where you can see that he&#x27;s looking for founding engineers. Rust has been a trending topic lately, which attracts relatively experienced engineers. He mentions that he made these experiences more than 2 years ago, so it&#x27;s notable that he waited so long to write about it. The slightly noisy &quot;ex-google&quot; and &quot;ex-apple&quot; mentions sound like advertisement.<p>And, well, the usual, &quot;learning curve&quot; and some largely hypothetical concerns about hiring. I developed a complex app with Rust with very high time pressure and with developers that didn&#x27;t have any previous Rust experience (I didn&#x27;t have much of it myself), it was risky but it worked out well, so I know first hand that it&#x27;s possible. And we are not &quot;ex-google&quot;!

OT, but I thought it was neat how all the splash images were just casually generated by dall-e and the author didn&#x27;t feel the need to mention it because it&#x27;s just normal now<p>(Not &#x2F;s, I genuinely think it&#x27;s cool things are like this now)

If you foresee cloud costs being among your top expenses, by all means use Rust.

Languages like Python can go a long way for a startup and is my first choice. Rewrite in Rust when it&#x27;s clear that the API is stable and performance starts to matter.

Over the past 2 years I&#x27;ve been writing Rust services for my own startup. Some were straightforward CRUD, some advanced language parsing and ML services. Some thoughts:<p>- Rust tends to push you to make good decisions. In my case, one of these good decisions was to ditch an ORM (which has always slowed me down) and instead write Postgres queries directly via SQLx. The compile time checks against an actual DB helped my speed dramatically<p>- Free performance can be a really big help when you are trying to figure out an API or algorithm. It&#x27;s really helpful to know that my unoptimized code won&#x27;t tank the server, and also helps me save costs on the cloud.<p>- &quot;It doesn&#x27;t compile, or it doesn&#x27;t break&quot; is kinda a mantra for Rust, and really helps me focus on problems at hand, instead of hunting down bugs.<p>&gt; You will have a hard time hiring Rust developers.<p>I&#x27;ve found that there is a drastic difference between hiring devs willing to learn Rust, and devs that want to work with you because you are using Rust. The bar of those devs that seek out a Rust position tends to be very high.<p>&gt; We made a huge mistake early on by adopting Actix as the web framework for our service...(To be fair, this was a few years ago and maybe things have improved by now.)<p>Actix-web has gone through some version-churn, but it&#x27;s never been &quot;buggy&quot; in my experience. The experience multiple years ago is vastly different than today, but even my older services written years ago with Actix-web are still running fine.<p>&gt; Libraries and documentation are immature.<p>Perhaps in years past, but I&#x27;ve always found the docs for Rust and its libraries to be very good. Folks write entire books on elements of Rust, and the standardization of the display of crate docs keeps things consistent.<p>&gt; Rust makes roughing out new features very hard.<p>The &quot;json!&quot; macro can come in handy here. Also Github Copilot is a godsend for this.<p>&gt; What really bites is when you need to change the type signature of a load-bearing interface and find yourself spending hours changing every place where the type is used only to see if your initial stab at something is feasible. And then redoing all of that work when you realize you need to change it again.<p>Hours? These type of corrections are spoonfed to you via errors at compile, or via the IDE. I&#x27;ve never had to spend hours on this. Everyone of these changes could be a bug, and having a typesafe language is a huge help here.<p>I recognize I might be in the minority, but I&#x27;ve really enjoyed using Rust for services for my startup. It&#x27;s helped me move fast, but maybe I&#x27;m a special case. I&#x27;m curious to hear other&#x27;s experiences.

Using Rust for startup is pre optimization at the language level.<p>You should be using the language you know best or dynamic languages when you are trying to move fast.

Yeah. And I also edit my VB in nano.<p>Jokes aside. This is a thoughtful and interesting article. I was wavering on going down the Rust path for my SaaS start-up. Glad I didn&#x27;t in the end for exactly the same kind of reasons.

s&#x2F;rust&#x2F;scala

Rule number one at startups: write things that don’t scale and use mature, boring frameworks&#x2F;languages.<p>The goal is to deliver products and iterate as fast as possible. Productivity is key to success.<p>IF (and it is a big IF) your startup ever gets to the point of having to scale up (nice problem to have) then just throw money at AWS, hire senior engineers and let them figured it out.<p>What matters is customer experience; nobody cares of what’s behind the scene.