Elixir and Haskell are two very powerful, very popular programming languages. However, each has its strengths and weaknesses. Whilst they are similar in a few ways, it’s their differences that make them more suitable for certain tasks.
Here’s an
Elixir vs Haskell
comparison.
Elixir vs Haskell: a comparison
Core philosophy and design goals
Starting at a top-level view of both languages, the first difference we see is in their fundamental philosophies. Both are functional languages. However, their design choices reflect very different priorities.
Elixir is designed for the real world. It runs on the Erlang VM (BEAM), which was built to handle massive concurrency, distributed systems, and applications that can’t afford downtime, like telecoms, messaging platforms, and web apps.
Elixir prioritises:
-
Concurrency-first – It uses lightweight processes and message passing to make scalability easier.
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Fault tolerance – It follows a “Let it crash” philosophy to ensure failures don’t take down the whole system.
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Developer-friendly – Its Ruby-like syntax makes functional programming approachable and readable.
Elixir is not designed for theoretic rigidness—it’s practical. It gives you the tools you need to build robust, scalable systems quickly, even if that means allowing some flexibility in functional integrity.
Haskell, on the other hand, is all about mathematical precision. It enforces a pure programming model. As a result, functions don’t have side effects, and data is immutable by default. This makes it incredibly powerful for provably correct, type-safe programs, but it also comes with a steeper learning curve.
We would like to clarify that Elixir’s data is also immutable, but it does a great job of hiding that fact. You can “reassign” variables and ostensibly change values, but the data underneath remains unchanged. It’s just that Haskell doesn’t allow that at all.
Haskell offers:
-
Pure functions – No surprises; given the same input, a function will always return the same output.
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Static typing with strong guarantees – The type system (with Hindley-Milner inference, monads, and algebraic data types) helps catch errors at compile time instead of run time.
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Lazy evaluation – Expressions aren’t evaluated until they’re needed, optimising performance but adding complexity.
Haskell is a language for those who prioritise correctness, mathematical rigour, and abstraction over quick iterations and real-world flexibility. That does not mean it’s slower and inflexible. In fact, experienced Haskellers will use its strong type guarantees to iterate faster, relying on its compiler to catch any mistakes. However, it does contrast with Elixir’s gradual tightening approach. Here, interaction between processes is prioritised, and initial development is quick and flexible, becoming more and more precise as the system evolves.
Typing: dynamic vs static
The next significant difference between Elixir and Haskell is how they handle types.
Elixir is dynamically typed. It doesn’t require explicitly declared variable types; it will infer them at run time. As a result, it’s fast to write and easy to prototype. It allows you to focus on functionality rather than defining types up front.
Of course, there’s a cost attached to this flexibility. If variables are computed at run time, any errors are also only detected then. Mistakes that could have been caught earlier come up when the code is executed. In a large project, this can make debugging a nightmare.
For example:
def add(a, b), do: a + b
IO.puts add(2, 3) # Works fine
IO.puts add(2, "three") # Causes a runtime error
In this example, “three” is a string but should’ve been a number and is going to return an error. Since it doesn’t type check at compile time, the error will only be caught when the function runs.
Meanwhile, Haskell uses static typing, which means all variable types are checked at compile time. If there’s a mismatch, the code won’t compile. This is very helpful in preventing many classes of bugs before the code execution.
For example:
add :: Int -> Int -> Int
add a b = a + b
main = print (add 2 3) -- Works fine
main = print (add 2 "three") -- Compile-time error
Here, the compiler will immediately catch the type mismatch and prevent runtime errors.
Elixir’s dynamic typing gives you faster iteration and more flexible development. However, it doesn’t rely only on dynamic typing for its robustness. Instead, it follows Erlang’s “Golden Trinity” philosophy, which is:
-
Fail fast instead of trying to prevent all possible errors.
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Maintain system stability with supervision trees, which automatically restart failed processes.
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Use the BEAM VM to isolate failures so they don’t crash the system.
Haskell’s static typing, on the other hand, gives you long-term maintainability and correctness up front. It’s particularly useful in high-assurance software projects, where errors must be kept to a minimum
before
execution.
In comparison, Elixir is a popular choice for high-availability systems. Both are highly reliable, but the former is okay with failure and relies on recovery at runtime, whilst the latter enforces correctness at compile-time.
Concurrency vs parallelism
When considering
Haskell vs Elixir, concurrency
is one of the biggest differentiators. Both Elixir and Haskell are highly concurrent but take different approaches to it. Elixir is built for carrying out a massive number of processes simultaneously. In contrast, Haskell gives you powerful—but more manual—tools for parallel execution.
Elixir manages effortless concurrency with BEAM. The Erlang VM is designed to handle millions of lightweight processes at the same time with high fault tolerance. These lightweight processes follow the actor model principles and are informally called “actors”, although Elixir doesn’t officially use this term.
Unlike traditional OS threads, these processes are isolated and communicate through message-passing. That means that if one process crashes, BEAM uses supervision trees to restart it automatically while making sure it doesn’t affect the others. This is typical of the ‘let it crash’ philosophy, where failures are expected and handled. There is no expectation to eliminate them entirely.
As a result, concurrency in Elixir is quite straightforward. You don’t need to manage locks, threads, or shared memory. Load balancing is managed efficiently by the BEAM scheduler across CPU cores, with no manual tuning required.
Haskell also supports parallelism and concurrency but it requires more explicit management. To achieve this, it uses several concurrency models, including software transactional memory (STM), lazy evaluations, and explicit parallelism to efficiently utilise multicore processors.
As a result, even though managing parallelism is more hands-on in Haskell, it also leads to some pretty significant performance advantages. For certain workloads, it can be several orders of magnitude faster than Elixir.
Additionally, Cloud Haskell extends Haskell’s concurrency model beyond a single machine. Inspired by Erlang’s message-passing approach, it allows distributed concurrency across multiple nodes, making Haskell viable for large-scale concurrent systems—not just parallel computations.
Scaling and parallelism continue to be one of the headaches of distributed programming. Find out what the others are.
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Best-fit workloads
Both Haskell and Elixir are highly capable, but the kinds of workloads for which they’re suitable are different. We’ve seen how running on the Erlang VM allows Elixir to be more fault-tolerant and support massive concurrency. It can also run processes along multiple nodes for seamless communication.
Since Elixir can scale horizontally very easily—across multiple machines—it works really well for real-time applications like chat applications, IoT platforms, and financial transaction processing.
Haskell optimises performance with parallel execution and smart use of system resources. It doesn’t have BEAM’s actor-based concurrency model but its powerful programming features that allow you to make fine-grained use of multi-core processors more than make up for it.
It’s perfect for applications where you need heavy numerical computations, granular control over multi-core execution, and deterministic performance.
So, where Elixir excels at processing high volumes of real-time transactions, Haskell works better for modelling, risk analysis, and regulatory compliance.
Ecosystem and tooling
Both Elixir and Haskell have strong ecosystems, but you must have noticed the theme running through our narrative. Yes, both are designed for different industries and development styles.
Elixir’s ecosystem is practical and industry-focused, with a strong emphasis on web development and real-time applications. It has a growing community and a well-documented standard library, supplemented with production-ready libraries.
Meanwhile, Haskell has a highly dedicated community in academia, finance, human therapeutics, wireless communications and networking, and compiler development. It offers powerful libraries for mathematical modelling, type safety, and parallel computing. However, tooling can sometimes feel less user-friendly compared to mainstream languages.
For web development, Elixir offers the Phoenix framework: a high-performance web framework designed for real-time applications, which comes with built-in support for WebSockets and scalability. It follows Elixir’s functional programming principles but keeps development accessible with a syntax inspired by Ruby on Rails.
Haskell’s Servant framework is a type-safe web framework that leverages the language’s static typing to ensure API correctness. While powerful, it comes with a steeper learning curve due to Haskell’s strict functional nature.
Which one you should choose depends on your project’s requirements. If you’re looking for general web and backend development, Elixir’s Phoenix is the more practical choice. For research-heavy or high-assurance software, Haskell’s ecosystem provides formal guarantees.
Maintainability and refactoring
It’s important to
manage technical debt
while keeping software maintainable. Part of this is improving quality and future-proofing the code. Elixir’s syntax is clean and intuitive. It offers dynamic typing, meaning you can write code quickly without specifying types. This can make runtime errors harder to track sometimes, but debugging tools like IEx (Interactive Elixir) and Logger make troubleshooting straightforward.
It’s also easier to refactor because of its dynamic nature and process isolation. Since BEAM isolates processes, refactoring can often be done incrementally without disrupting the rest of the system. This is particularly handy in long-running, real-time applications where uptime is crucial.
Haskell, on the other hand, enforces strict type safety and a pure functional model, which makes debugging less frequent but more complex. As we mentioned earlier, the compiler catches most issues before runtime, reducing unexpected behaviour.
However, this strictness means that refactoring in Haskell must be done carefully to maintain type compatibility, module integrity, and scope resolution. Unlike dynamically typed languages, where refactoring is often lightweight, Haskell’s strong type system and module dependencies can make certain refactorings more involved, especially when they affect function signatures or module structures.
Research
on Haskell refactoring highlights challenges like name capture, type signature compatibility, and module-level dependency management, which require careful handling to preserve correctness.
Then, there’s pattern matching, which both languages use, but do it differently.
Elixir’s pattern matching is flexible and widely used in function definitions and control flow, making code more readable and expressive.
Haskell’s pattern matching is type-driven and enforced by the compiler, ensuring exhaustiveness but requiring a more upfront design.
So, which of the two is easier to maintain?
Elixir is better suited for fast-moving projects where codebases evolve frequently, thanks to its fault-tolerant design and incremental refactoring capabilities.
Haskell provides stronger guarantees of correctness, making it a better choice for mission-critical applications where stability outweighs development speed.
Compilation speed
One often overlooked difference between Elixir and Haskell is how they handle compilation and code updates.
Elixir benefits from BEAM’s hot code swapping, where updates can be applied without stopping a running system. Additionally, Elixir compiles faster than Haskell because it doesn’t perform extensive
type checking
at compile time.
This speeds up development cycles, which is what makes Elixir well-suited for projects requiring frequent updates and rapid iteration. However, since BEAM uses Just-In-Time (JIT) compilation, some optimisations happen at runtime rather than during compilation.
Haskell, on the other hand, has a much stricter compilation process. The compiler performs heavy type inference and optimisation, which increases compilation time but results in highly efficient, predictable code.
Learning curve
Elixir is often considered easier to learn than Haskell. Its syntax is clean and approachable, especially if you’re coming from Ruby, Python, or JavaScript. The dynamic typing and friendly error messages make it easy to experiment without getting caught up in strict type constraints.
Haskell, on the other hand, has a notoriously steep learning curve. It requires a shift in mindset, especially for those unfamiliar with pure functional programming, monads, lazy evaluation, and advanced type systems. While it rewards those who stick with it, the initial learning experience can be challenging, even if you’re an experienced developer.
Metaprogramming
Both Elixir and Haskell allow you to write highly flexible code, but they take different approaches.
Elixir provides macros, which you can modify and extend the language at compile time. This makes it easy to generate boilerplate code, create domain-specific languages (DSLs), and build reusable abstractions. However, improper use of macros can make code harder to debug and maintain.
Haskell doesn’t have macros but compensates with powerful type-level programming. Features like type families and higher-kinded types allow you to enforce complex rules at the type level. This enables incredible flexibility, but it also makes the language even harder to learn.
Choosing between the two
As you’ve seen, both Elixir and Haskell can be great, if used correctly in the right circumstances.
If you do choose Elixir, we’ve got a great resource that discusses how Elixir and Erlang—the language that forms its foundation—can help in future-proofing legacy systems. Find out how their reliability and scalability make them great for modernising infrastructures.
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Erlang Solutions team
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Elixir vs Haskell: What’s the Difference?
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