Comparing Rust and Scala

Rust and Scala are popular programming languages with wide adoption and use cases, both appreciated for their excellent support for concurrency, speed, expressivity, and scalability.

Rust and Scala were built as alternatives to powerful languages that have acquired technical debt and lack modern programming practice.

This article will compare Rust and Scala to give you insights into their use cases, why and when you should use either of them, and much more.

To jump ahead:

• What is Rust?
• Rust’s features
• Anatomy of a simple Rust program
• Popular Rust use cases
• What is Scala?
• Scala’s features
• Anatomy of a simple Scala program
• Popular Scala use cases
• Comparing Scala and Rust

What is Rust?

Rust is a fast, statically typed, compiled, multi-purpose programming language, primed for its speed, memory safety, concurrency model, and rich type system.

Rust has been the most loved programming language on the Stack Overflow developer survey since 2016, owing to its many benefits. Rust supports multiple programming paradigms, provides good expressive prowess, and has a syntax that is easy to understand and use.

Rust was designed to fix the criticisms of C++, and the language is widely used in systems programming for targeting low-resource devices. Rust is used on web frontends (via WebAssembly) to run high-performance web applications and, on the backend, for fast I/O operations, building distributable command-line applications, and networking for performance and reliability.

Rust’s features

Rust is going mainstream, and many companies and developers are using it in their projects — here are some of the reasons why.

Memory safety

Rust is neither garbage compiled, nor does it allow express memory management, like C and C++ do. Rust uses an ownership model for memory management and a borrow checker for enforcing the ownership rules, which are a set of rules that the compiler checks at compile time.

The ownership model and the borrow checker ensure that Rust programs are memory-safe and efficient. Although they contribute to the steep learning curve of Rust — especially if you’re coming from a garbage-compiled language — you’ll get to appreciate the borrow checker and understand why developers love Rust as you write more code.

Concurrency

Concurrency in modern programming languages like Rust and Go is one selling point. Concurrency isn’t a new trend, and modern programming languages have implemented desirable patterns.

Rust’s fearless concurrency concept handles concurrency uniquely and helps maximize performance and minimize errors with abstractions that serve many use cases. Rust provides functionality for creating threads, communication between threads, and a shared state between threads using arcs and mutexes, all built into the standard library.

The compiler guarantees Rust programs are data race-free and concurrent programs don’t misbehave.

Rust’s interoperability

Rust is interoperable with many languages, like C and C++, through its foreign function interface (FFI). Interoperating with C requires that you wrap the exposed C API or build the code for Rust integration. C++ doesn’t have a stable application binary interface (ABI), so you’ll have to use the C ABI.

C and C++ are popular languages used in many codebases. As they get older and become unpleasant to work with due to acquired technical debts, modern programming languages need to interoperate with them for continued prosperity. Rust matches up to most features and experiences with C and C++, making it a viable option or replacement.

Performance

Rust is often compared to languages like Go, C++, and Zig in terms of performance. Performance is one reason Rust is suitable for a wide range of use cases, especially embedded systems and web applications.

According to programming language and compiler benchmarks, without parallelization, these are the benchmarks from printing helloworld and binarytrees, respectively.

Anatomy of a simple Rust program

Getting started with Rust is easy. The installation instructions and everything you’ll need to become a pro at Rust programming are provided in the Rust book.

Here’s a minimal “Hello, world!” program in Rust:

fn main() {
    println!(“Hello, world!”);
}

The entry point of a Rust program is the main function, and the println! macro prints the text on a new line.

You’ll also find many Rust resources, from web development to blockchain, and many others, on the Rust section of the LogRocket blog.

Popular Rust use cases

Developers love Rust and, thus, use the language in many use cases. Here are a few famous use cases for Rust.

Web development

Whether it’s the frontend or backend of your web application, you can use Rust. The Rust ecosystem is home to fantastic frontend frameworks, like stdweb, for communicating with DOM APIs, Yew, backend frameworks such as Actix, Rocket, and Warp, and full-stack frameworks like Yew, Percy, and MoonZoon, partly powered by WebAssembly.

Blockchain development

Because it is a safety-first, highly efficient language with modern programming practices, Rust is suitable for building blockchains and decentralized applications.

Rust is the primary language for building applications on Polkadot and Solana, and you’ll find Rust SDKs for building many other popular blockchains.

Embedded systems programming

Rust is prevalent and slowly replacing C and C++ in embedded systems programming. Rust’s low-level expressiveness established the language as a great choice for building embedded systems, especially for IoT devices. There are even many projects in the Rust ecosystem for building on microcontrollers, including Arduino.

In many other fields, developers love to use Rust; most libraries are often easy to use and inspired by older libraries that developers are comfortable using. The Rust ecosystem is still very young, and many libraries are still developing.

Pros of using Rust

Here’s an overview of the reasons developers love Rust.

1. Compared to many other languages, Rust is concise and very flexible. It’s easy to implement any design patterns in Rust. Rust also has generics implemented in the standard library
2. Concurrency is a feature to consider when choosing a systems programming language, and Rust provides concurrency features with safety
3. Rust is fast and highly efficient compared to modern and older programming languages. You’ll often find Rust being compared to C, C++, and Go in terms of speed, with benchmarks where Rust often triumphs
4. The Rust development team prioritizes and guarantees backward compatibility for the language. The Rust’s crater tool compiles and tests crates to ensure that newer versions are compatible with all crates
5. The ownership model and Rust borrow checker are a feature that developers love about Rust. Memory safety is an issue in C and C++, and lack of flexibility is the order in garbage compiled languages. Rust solves these issues

Cons of using Rust

It’s not all roses and bluebirds with Rust; there are some cons to consider before using.

1. Beginner-friendly? Not Rust! Rust has a very steep learning curve. There are many new concepts to adapt to, no matter the language you’re coming from. The borrow checker can also be very frustrating for beginners
2. Rust is not a language you might choose if you’re thinking about developer productivity. Good things take time, just like Rust programs, and if you want to build a product fast, you’re better off with Go, JavaScript, etc.
3. Rust is a relatively new language, and although its features are promising, the Rust ecosystem is still very immature for many of the use cases you may want to explore with it
4. As program size increases, the compile time for Rust programs can be quite long. This is because the borrow checker must verify that a program and all its dependencies are memory-safe

With these cons, many developers still choose Rust as their favorite language. You’ll want to consider if any of the cons affect your reasons to use Rust, and consider tradeoffs.

What is Scala?

Scala (scalable language) is a multi-paradigm, strong, statically typed, general-purpose programming language designed to address the fallouts of Java. Scala is concise and designed to grow based on user demand.

Scala runs on the Java Virtual Machine (JVM), meaning you can write Scala code to run anywhere. Scala also has a compiler that compiles Scala code into Java byte code for execution and an interpreter.

Scala provides features in object-oriented languages (every value is an object) and functional programming, similar to Haskell.

You can compile Scala code to Java bytecode and run it on the JVM (Java Virtual Machine), where the language has bidirectional interoperability with Java, to use existing Java libraries in Scala and Scala libraries in Java.

Developers and companies use Scala across many use cases, like machine learning, finance, full-stack web development, data processing, distributed systems, and many others.

Scala’s features

Scala is an elegant programming language that offers a wide range of features with simplicity.

Scala is what would happen if there were a Genie that eavesdropped on every Java developer as they cursed when their build broke due to a missing semicolon, then inferred a wish from their complaints – Knewton.

Here are a few excellent features of Scala that make the language desirable to work with.

Functional programming

Scala is one of the few object-oriented languages that also provides functional programming features out of the box, increasing its expressivity. Scala provides functional programming features, including immutability, currying, pattern matching, lazy evaluation, and an advanced type system that supports anonymous types, algebraic types, higher-order types, operator overloading, named parameters, optional parameters, and algebraic effects.

The multi-paradigm nature of Scala is one of the selling points of the language, also making it suitable for academic purposes and a more comprehensive range of use cases.

Cross-language interoperability

Scala is one of the most interoperable languages. Scala is interoperable with Java, JavaScript, and the .NET framework. Also, you can run Scala on LLVM (beta at the moment).

Because Scala is part of the JVM ecosystem, it was a good development decision to make Scala code interoperable with Java. And because Java is interoperable with .NET, Scala is equally interoperable with .NET.

For frontend web applications, you can compile Scala to JavaScript for execution in the browser or compile Scala to WebAssembly to bypass JavaScript and run Scala directly in the browser. The Scala ecosystem is also home to some backend web frameworks, offering the full-stack experience.

Interoperability enables Scala developers to use Scala programs for many use cases without having to use or learn new languages.

Concurrency

Scala’s concurrency model is built on Java’s concurrency model. You can run unlimited threads on a machine, and threads aren’t the only option for concurrency in programs — you can also use Scala’s features and feature actors to make your programs concurrent with increased flexibility. The multiple options Scala provides for concurrency make it a viable option for data processing and many other applications.

Anatomy of a simple Scala program

Every Scala program starts with the main method, the object, and an expression.

object LogRocket {
  def main(args: Array[String]) {
    println(“Hello world!”)
  }
}

The array is the list of command-line arguments you can use based on your operation, and the println method prints the data argument in a new line.

Popular Scala use cases

Big data processing

Scala shines the most when the subject is big data processing because it provides functional programming. Big data solutions like Apache Spark, Kafka, and Flink are written in Scala because Scala provides functionalities for working with large data sets.

Web development

You can build full-stack web applications with Scala. There are frontend web and backend frameworks, and because Scala is interoperable with JavaScript, it’s easier to build web applications in Scala.

You can use JavaScript everywhere

Scala programs are interoperable with Java, so you can use Scala instead of Java to keep the features you love about Scala, and make your programs easier to build and maintain.

Pros of using Scala

There are so many reasons you’ll love Scala. Here are a few of the reasons Scala is famous:

1. Compared to Java and most functional programming languages, Scala code is more readable and concise
2. Scala’s interoperability with other languages and platforms gives it an edge because you can write programs once and run them anywhere
3. Scala is very scalable, and because it combines multiple paradigms, there’s an increase in idea expressivity. You can use Scala to build fault-tolerant, highly concurrent systems
4. Scala’s multi-paradigm nature makes the language useful for many use cases and fields

Cons of using Scala

You’ll hardly find developers writing Scala code for a language as aesthetic as Scala. Here’s why:

1. Although Scala has been around for over 17 years, the Scala ecosystem is still developing, and it is challenging to find Scala developers
2. Scala has a tough learning curve, and you might not fully appreciate it and its functionalities if you haven’t used a JVM language like Java or Kotlin before
3. Scala inherits some of Java’s demerits, especially the JVM’s demerits, including the no proper tail-recursive optimization

Nonetheless, Scala has found applications in high-end technologies, and many companies are investing in using the language as part of their infrastructure.

Comparing Scala and Rust

Scala and Rust share many similarities, and you can use both languages for some of the same use cases without compromising essential features. While Scala has found its most popular application in big data, data processing, and stream processing, Rust has found its buzz in more performant applications like game development, blockchain development, and embedded systems programming.

You’ll want to use the right tools for the right job, so you won’t want to use Scala where Rust shines, and vice versa. Your choice should be based on the use case, expressivity, developer community support, and the libraries that suit your use case.

You can comfortably use either language for web development because their ecosystem is home to many powerful web frameworks.

	Scala	Rust
Expressiveness	Very expressive and flexible	Expressive and flexible
Paradigm	Functional and object-oriented	Object-oriented and concurrent
Type system	Strongly, statically typed	Strongly, statically typed with generics
Popular use cases	Data processing, distributed systems, web development, etc.	General-purpose applications, web and server-side applications, blockchain development, gaming, etc.

According to the Stack Overflow developer survey, Scala and Rust are in the top ten most paid-for programming languages, proving that the languages are highly valued and in demand.

My advice is to choose Scala if you’ve worked with a JVM-based language before, especially Java, to get the most out of Scala and persist through the learning and mastery process.

You can choose Rust if you’re an explorer and want to try out a new language with prospects. The Rust train is only just getting started, more developers are getting on board, and the community is expanding the ecosystem of crates and libraries for a smoother Rust experience across more fields.

Conclusion

This article taught you about Scala and Rust, their features, use cases, pros and cons, and gave you a comparison between the two languages for your next project.

Rust and Scala are excellent programming languages — whichever you choose, you’re bound to have a worthwhile experience.