When comparing Rust vs Erlang, the Slant community recommends Rust for most people. In the question“What is the best programming language to learn first?” Rust is ranked 21st while Erlang is ranked 44th. The most important reason people chose Rust is:
Since Rust is statically typed, you can catch multiple errors during compile time. This is extremely helpful with debugging, especially compared with dynamically typed languages that may fail silently during runtime.
Specs
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Pros
Pro Catch errors at compile-time
Since Rust is statically typed, you can catch multiple errors during compile time. This is extremely helpful with debugging, especially compared with dynamically typed languages that may fail silently during runtime.
Pro Compiles to machine code allowing for extra efficiency
Rust uses LLVM as a backend, among other things this allows Rust code to compile down to machine languages. This allows developers to write programs that run as efficiently as possible.
Pro Threads without data races
Unique ownership system guarantees a mutable data to be owned and mutated by only one thread at a time, so there's no data race, and this guarantee is checked at compile time statically. Which means easy multi-threading.
Of course, immutable data can be shared among multiple threads freely.
Pro Generics support
You don't have to write same array and dictionary classes hundreds and thousands times for strong type check by compiler.
Pro Built-in concurrency
Rust has built-in support for concurrency.
Pro Supports cross compilation for different architectures
Since Rust 1.8 you can install additional versions of the standard library for different targets using rustup/multirust
.
For example:
$ rustup target add x86_64-unknown-linux-musl
Which then allows for:
$ cargo build --target x86_64-unknown-linux-musl
Pro Makes developers write optimal code
Rust is a modern programming language written around systems. It was designed from the ground up this way. It's language design makes developers write optimal code almost all the time, meaning you don't have to fully know and understand the compiler's source code in order to optimize your program.
Furthermore, Rust does not copy from memory unnecessarily, to give an example: all types move by default and not copy. Even references to types do not copy by default. In other words, setting a reference to another reference destroys the original one unless it's stated otherwise.
Pro Support for macros
When you identify a part of your code which gets repeated often, which you cannot abstract using functions or classes, you can use Rust's built-in Macros.
Pro Official package manager and build tool
Cargo is the official package manager for Rust. It comes with the language and downloads dependencies, compiles packages, and makes and uploads distributable packages
Pro Easy to write understandable code
While not as verbose as Java, it still is much more verbose than languages like Go and Python. This means that the code is very explicit and easy to understand.
Pro Big community
The biggest community contributing to language.
Pro Functional programming
Very easy to create functional with some additional from structure application.
Pro Excellent syntax
Pro Safety
Pro No GC
Pro Low memory usage
Pro Static compiled & statically linked single file output
Pro Extremely fast code execution
Pro Zero-cost futures or Async IO
Pro Built from the ground up with concurrency and distributed computing in mind
Erlang has strong roots with the telecom industry in which concurrent processes are normal. It's designed to be concurrent, to be used for distributed computing and to be scalable.
Pro Fault-tolerant
Fault tolerance means that a system has the property to continue operating even though one or more components have failed.
For Erlang systems, this means that the system is kept running even if for example a user has to drop a phone call rather than forcing everyone else to do so.
In order to achieve this, Erlang's VM gives you:
- Knowledge of when a process died and why that happened
- The ability to force processes to die together if they depend on each other and if one of them has a fault.
- A logger that logs every uncaught exception
- Nodes that can be monitored so that you find out when they go down
- The ability to restart failed processes (or groups of them)
Pro Upgrade code without stopping the system
In a real-time system it may not be possible to stop the system in order to implement code upgrades. For these cases Erlang gives you dynamic code upgrade support for free when using OTP. The mechanism is very easy to understand and works as follows:
- Start the app
- Edit the code
- Recompile
That's all that is needed, the app updates with the new code while it's still running and tests are run automatically.
Pro Great for writing distributed applications
Erlang is made to be parallel and distributed. Because it's very easy to write code that uses multiple processor cores, it's also very easy to write applications that span multiple servers.
Pro Battle proven
Erlang has been used in production for more than 20 years now. During that time it has proven itself over and over again that works great in both small startups and large-scale enterprise systems.
Erlang has been used extensively by Ericsson themselves. For example, the AXD301 ATM, which is one of Ericsson's flagships is probably the largest Erlang project ever with more than 1.1 million lines of Erlang code.
Pro Light processes
Erlang's processes have very little overhead (about 500 bytes per process). This means that a huge amount of processes can be created, even on older machines.
Pro Consistency across platforms
Erlang's processes run in a complete independent way from the OS (they aren't managed by the OS scheduler neither). This means that programs written in Erlang will run exactly the same way regardless of the operating system or platform.
Cons
Con Long compile times
Way longer to compile than other languages.
Con Low productivity
The compiler is strict, such as ownership and borrowing checkers.
Con Low readability
Harder to read and understand language.
Con Very ugly and verbose syntax
Compared to many languages. One tool needed to be productive is the language to be pleasing and effective, yet Rust friction is as high as its safety.
Con Steep learning curve
Pretty strict and hard to adapt for beginners.
Con Not as useful or productive as advertised.
If really out here wanting to use something besides C/C++, in 98% of use cases, would do just as well or be better off using something other than Rust. Will complete the project faster, would be easier, will be happier, and nearly as safe (use newer language with optional GC).
Con Rust not as safe as it pretends to be
Rust problems:
1) Massive undisclosed usage of unsafe.
2) Massive amounts of memory safety CVEs - see details.
3) Large bloated Rust binaries increase attack surface for exploits.
4) Many corporate types claiming Rust is safe, don't actually program or use it (have some quiet financial interest to push it).
Con Significant time required to understand the language fully
There's the infamous borrow checker for example.
Con Low-level programming language
This means that it encourages the programmer to be very careful in terms of how memory is allocated, etc.
Most applications can run without exceeding the capacity of the server, even with an inefficient dynamic scripting language.
Con Eccentric syntax
Erlang's syntax may feel very strange to 99% of programmers who have never used it. This is because it does not share any similarities or common syntax definitions that are found in all the other languages that are used today.
Con Useful in only one niche
Erlang is not really a general purpose language. It has a very special and well-defined niche where it towers above everything else. It's specialized in scalability and in distributed applications. Which is not necessarily a bad thing per se, but it still lacks and falls behind other languages when it needs to do things outside it's niche.