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**Elm** is a programming language. It is a purely functional language that compiles to JavaScript. Developers can use this language for different purposes. 
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## Main uses of Elm 
Some of the services of Elm language are as follows: 


- It is useful in front-end Development.
- It is useful for building web-based graphical user interfaces.
- It is useful for building web applications.
- It is useful for building websites.




![](/api/edpresso/shot/5643526824263680/image/5944131719528448)

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## Why a functional language?
Some benefits of using a functional language like Elm are as follows:


- It gives no runtime errors in practice.
- It gives obliging error messages.
- It provides definitive refactoring.
- It can automatically enforce semantic versioning for all Elm packages.



![](/api/edpresso/shot/5643526824263680/image/5481831371898880)

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## Code example
Below is a simple hello world program in Elm language:

import React from 'react';
import { shallow, configure } from 'enzyme';
import Adapter from 'enzyme-adapter-react-16';

configure({ adapter: new Adapter() });

import HelloWorld from './app';

var TestResult = function() {
    this.succeeded = false;
    this.reason = "";
    this.input = "";
    this.expected_output = "";
    this.actual_output = "";
}

export const executeTests = function() {

  var results = [];

  result = new TestResult();
  result.input = 'HelloWorld Component';
  result.expected_output = "span containing text 'Hello World'"

  let wrapper = shallow(<HelloWorld />);

  // Call your Challenge function here.

  let type = wrapper.type();
  let testSuccessful = true;
  let failureReason;

  if (type !== 'span') {
    testSuccessful = false;
    failureReason = "You need to render exactly one span HTML element";
  } else if (wrapper.props().children != "Hello World") {
     testSuccessful = false;
     failureReason = "You have rendered wrong message in your span element";
  }

  result.actual_output = wrapper.html();

  if (testSuccessful) {
    result.succeeded = true;
    result.reason = "Succeeded"
  } else {
    result.succeeded = false;
    result.reason = failureReason;
  }

  results.push(result);

  return results;
}


React

Dart

GoJS React

Typescript React

Vue.js

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## Code explanation
- **Line 3:** We import the `Html exposing (text)` library for printing text.
- **Line 5:** We print the string `Hello, World!`.

What is Elm?

Elm is a functional programming language compiling to JavaScript, ideal for front-end development and building web interfaces and applications.