Elm uses functional reactive programming to manage state and UI.

Its type system eliminates runtime exceptions for well-typed programs.

Elm promotes a clear architecture (The Elm Architecture) for predictable, maintainable applications.

Immutable values and functions

Algebraic data types (custom types and unions)

Pattern matching for control flow

Signals and subscriptions for reactive programming

Module system for code organization

Immutable variables and constants

Pure functions

Custom types and unions

Pattern matching for control flow

The Elm Architecture: Model, Update, View

src/ directory for Elm modules

elm.json for project configuration

Main.elm as entry point

Test/ directory for unit tests

Assets and static files for front-end

Define the Model to represent state

Create Update functions for state transitions

Write View functions for rendering UI

Manage side effects with commands and subscriptions

Compile Elm code to JavaScript and serve in browser

Beginner: simple UI with static data

Intermediate: dynamic UI with interactive elements

Advanced: SPA with complex state management

Expert: real-time dashboards and subscriptions

Elm vs JavaScript: type-safe, no runtime errors

Elm vs React: pure functional architecture vs component-based

Elm vs TypeScript: Elm enforces immutability and no-null guarantees

Elm vs ReasonML: similar functional paradigms, Elm focused on front-end

Elm vs Angular/Vue: simpler, more maintainable architecture

2012 - Elm created by Evan Czaplicki

2013 - Elm 0.10 released with core architecture

2015 - Elm 0.17 introduces simplified TEA

2018 - Elm 0.19 stabilizes language with no breaking changes

Present - Elm continues to evolve with community contributions

Cmd: commands representing side effects

Sub: subscriptions for external events

Msg: message type for Update function

Model: application state

TEA: The Elm Architecture