For Complex Applications, Rust Is as Productive as Kotlin

https://ferrous-systems.com/blog/rust-as-productive-as-kotlin/

by quyleanh • 6 years ago

83 22 6 years ago

The title is misleading at best, utterly wrong at worst. This single biased (he's working on rust LSP and is part of ferrous system (their business model depend on rust adoption)) opinion has an insanely huge disclaimer: the productivity claim only stand for complex applications that does not depend on libraries... Large, complex app and building everything yourself is such a niche use I didn't knew it existed.

TheGoddessInari• 6 years ago

Rust-analyzer uses libraries, so I'm not sure what your point is.

fulafel• 6 years ago

Interesting report. One thing possibly limiting applicability of the lesson is that applications are very regular and closed systems and free from having to adapt to arbitrary irregularities of the real world.

Johanx64• 6 years ago

None of these articles ever come to mention compile times, which are crucial for productivity on both large and complicated projects, and those are absolutely attrocious for Rust.

Which is why I would avoid rust for anything where productivity is crucial.

rsa25519• 6 years ago

Which is why I would avoid rust for anything where productivity is crucial.

Surely we can be more nuanced than this? Compile times vary greatly between different projects and dependencies.

pdimitar4• 6 years ago

While I really like Rust, the compiler / linker performance has ways to go still. As somebody else here said, daily productivity is hugely important -- it's not all about the virtues of the language and/or the runtime.

Ever since I started using a language server on my Emacs (plus `rust-analyzer`) my flow has improved because I can almost immediately see compiler errors or warnings but `cargo run` and `cargo build` are still slower than they should be. Seems like no matter how strong your machine is, those final steps can never go below 6-7s. (I have a fairly modern Xeon workstation)

Those 7s of delay sound funny for many and I've been made fun of for mentioning it but I'll stand behind my statement: when you're in the productive speedy flow state, you need instant feedback. If you don't have it, you lose your motivation to iterate rapidly.

Even though I believe Rust to be the future of low-level and mega-fast computing, it still has nothing on the Go and OCaml compilers/linkers, sadly. Even Elixir -- a dynamic but compiled language -- feels near-instant when you use LSP.

pjmlp3• 6 years ago

Hence why I use a core duo with 8 GB, SSD to test Rust compiler improvements, using a toy project I ported from C++ into Rust.

C++ version, with binary dependencies, a couple of minutes, not longer than 5.

Rust version, as if has to compile the whole world, 16 minutes currently.

My measurement is against .NET Native, D, Delphi on similar hardware.

On positive note, Cranelift just got merged, that will certainly improve compile times.

avrionov• 6 years ago

Interesting statistics. How big is the toy project? How many lines of C++ code vs Rust code?

I expect to be fairly big project.

pdimitar4• 6 years ago

I keep around a reasonably midrange laptop (2nd/3rd gen i5 CPU, 8GB RAM, relatively okay SSD) to periodically test my stuff on and it has been a sanity saver on a few occasions, for the exact same reason as you. :)

qchris• 6 years ago

Maybe it's just because I'm not regularly re-building Rust projects with enormous changes, but I very rarely experience the compile time in Rust to be an issue compared with a language like C++ or even a Jupyter notebook that's re-evaluating a cell. I usually code with a bottle of water or cup of coffee nearby, and when I hit 'enter' on the 'cargo build/run' command, I often pick up my cup and take a sip. By the time I've put the mug back down, the compilation is usually over. So I guess the quantum of time when I'm coding is a sip of coffee, and anything less than the time it takes to do that feels functionally the same to me.

Granted, first-time compilation takes a while, but once that's taken care of, I don't update my toolchain often enough for it to have a noticeable impact on my workflow. I guess if you're getting a new nightly build every day and re-compiling everything, that might be a pain, but that doesn't seem to be the root of most people's complaints.

pdimitar4• 6 years ago

I am only talking about the "change a line -> recompile -> run -> inspect -> change a line ..." workflow.

As mentioned in my comment above, for most people waiting a few seconds is a funny non-issue but it directly affects my motivation to rapidly iterate.

The "take a sip" brain hack might work, I'll try it. :) But I try to follow rules for proper hydration which means that you shouldn't sip water every other minute -- there have to be pauses.

It's a good advice regardless. I'll see if I can adopt a variation of it.

trevyn• 6 years ago

There's a saying about Rust that it takes more effort to get a Rust program to compile without errors, but once it does, chances are it will work correctly. This seems counter-intuitive coming from other languages, but has been borne out by my experience. The strong typing and compiler guarantees push most run-time errors or unintended behavior to compile-time.

As a result, a lot of the iteration that happens is between me and `rust-analyzer` and `cargo check`, which, as you note, is much faster than a compilation pass with codegen and link.

andrewflnr• 6 years ago

That used to be a Haskell saying, and I suspect it's still more true there...

zcw100• 6 years ago

For everyone complaining about compile times I’d like to know how it compares to Scala.

icedchai• 6 years ago

I worked on a Scala project about 10 years ago. Compile times were atrocious.

vips7L• 6 years ago

They still are. My project is mostly Java and the scala part takes up most of the compilation. It might just be because javac isn't an optimizing compiler so it's fast (I'm not sure about scalac).

MHard• 6 years ago

It depends on your project. As soon as you add too many dependencies to rust with lots of macros, compile times tend to increase a lot for rust projects because it creates a fat binary, whereas it works fine for a mountain of dependencies in Scala for me.

On the other hand if you just need compiler errors, cargo check runs almost instantly for incremental checks.

For Complex Applications, Rust Is as Productive as Kotlin

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