Why I Hope I Get to Write a Lot of Elm Code in 2025

In a world dominated by React, Vue, and Svelte, it might seem strange to highlight Elm – a niche language that has existed since 2012 but has had fewer releases since then than React has in a year. But right now, when frontend development is becoming increasingly complex, and clients are doing heavy lifting that previously belonged on the other side of an API call, it’s worth taking a closer look at what Elm does right.

What is Elm? Link to heading

Elm is a functional programming language specifically designed for web applications. Here are the key differences from modern JavaScript frameworks:

• No runtime errors – When the code compiles, it can run without unexpected crashes
• Complete handling of all possible states – The compiler helps you with all edge cases
• Predictable architecture – The Elm Architecture (TEA) provides a clear structure that scales well
• Automatic version handling – The compiler detects breaking changes

React vs. Elm: Same Direction, Different Approach Link to heading

It’s fascinating to see how React has evolved in recent years:

• React introduced hooks to handle state more functionally
• Redux (inspired by Elm) became standard for complex state management
• TypeScript (strong typing) became almost mandatory for serious projects
• React Server Components isolate side effects on the server side

But there’s an important difference: React recommends functional programming and immutability, while Elm requires it. In React, you can still mutate variables and state, mix paradigms, and create runtime errors. In Elm, it’s simply impossible.

As a senior React developer recently told me: “Good React code in 2025 looks suspiciously like Elm code from 2015.”

When Constraints Give Freedom Link to heading

Ironically, Elm’s strict constraints give us several advantages:

• Simpler debugging: When data never changes, you don’t have to wonder “who or what changed this value?”

  // In JavaScript, this can happen:
  const user = { name: "Ada", age: 29 };
  someFunction(user); // user can be changed here
  console.log(user.name); // What's the name now? Impossible to know without reading someFunction
  

  In Elm, this is impossible - you get a compile-time error if you try to mutate:

  -- In Elm:
  user = { name = "Ada", age = 29 }
  
  -- This doesn't compile:
  user.name = "Grace"  -- ERROR: Elm doesn't have variable mutation.
  
  -- The right way in Elm:
  updatedUser = { user | name = "Grace" }  -- Creates a new copy with changed name
  

• Predictable code: Pure functions + immutable data = same input always gives same output

• Safer refactoring: The compiler finds all places that need to be updated

• Less mental load: You don’t need to keep the entire state history in your head

(And, as we know: JavaScript not only allows mutating, but also re-assigning variables that are not consts.)

SOLID by Default Link to heading

The Elm Architecture (TEA) is a simple but powerful model for building web applications. It consists of three main parts:

1. Model - The application’s state
2. Update - How the state changes in response to events
3. View - How the state is displayed in the user interface

Image source: Elm Guide

This pattern enforces SOLID principles – whether you want to or not:

1. Single Responsibility – Elm forces you to separate View, Update, and Model
2. Open/Closed – New functionality is added by extending the Msg type with new variants
3. Liskov Substitution – Automatically fulfilled through Elm’s type system and union types
4. Interface Segregation – Elm encourages small, focused modules and types
5. Dependency Inversion – All communication goes through messages (Msg) and abstractions

Where other languages offer SOLID as “best practices” you can follow if you’re disciplined, they are a mandatory part of Elm’s DNA. The compiler is your unforgiving architecture mentor.

The Elm Architecture vs. Clean Architecture Link to heading

Clean Architecture (CA) is about organizing code so that business logic is independent of frameworks and UI. How does TEA fit in here?

1. Separates UI from Logic Link to heading

• Just like CA, TEA has a clear separation between the presentation layer (View) and domain logic (Model + Update)
• This means you can change the UI without changing the domain logic

2. Structuring Business Logic Link to heading

• TEA doesn’t have an explicit “use case layer” as CA recommends
• But the Update function can be seen as an interactor in CA, where it takes in an event and determines a state change

3. Independence from External Systems Link to heading

• In Clean Architecture, business logic should be independent of databases, UI, or third-party APIs
• TEA ensures this by using Cmd for side effects, so API calls and similar are outside the core architecture

4. Simple Testing Link to heading

• Both architectures promote testable code
• TEA’s pure functional approach makes it easy to unit test the Update function without thinking about external dependencies

When Should You Consider Elm? Link to heading

Elm is particularly well-suited when:

1. You’re building a complex frontend application
2. Robustness and maintainability are critical
3. You have the opportunity to train your team
4. You’re starting a new project from scratch

The Challenges Link to heading

Let’s be honest about the challenges too:

• Steep learning curve for developers used to imperative programming
• Smaller ecosystem than React/Vue
• Fewer developers available
• Can be difficult to “sell” to decision-makers and stake-holders

Conclusion Link to heading

Elm’s relevance in 2025 lies not in market share, but as an architectural compass. Many of its principles are found in:

• React Server Components’ isolation of effects
• TypeScript’s increasingly strict type system
• The growth of compile-time tools like tRPC and Zod

Again: what various “best practices” encourage the driven developer to strive for, is a mandatory part of Elm. Sure, you can (and should!) write functional React with good architecture, strong types, and isolated side effects; with Elm, you simply aren’t allowed to do anything else.

Resources to Get Started Link to heading

• Elm Guide – The official guide
• Elm in Action – An excellent book for learning how Elm works in larger applications (I’m reading this right now, and I love it!)
• Elm Community – An unusually helpful and open community
• elm-spa – For building Single Page Applications
• Elm Land – New meta-framework