xElm

Exercism Exercises in Elm

Setup

The simplest way to install Elm is via Node.js/NPM.

If you don't already have Node.js installed on your computer, you can download it from the official site. Once you have Node.js up and running, follow these steps to install the Elm platform and elm-test.

$ npm install --global elm elm-test

Contributing

Thank you so much for contributing! 🎉

Please start by reading the general Exercism contributing guide.

We welcome pull requests that provide fixes and improvements to existing exercises. If you're unsure, then go ahead and open a GitHub issue, and we'll discuss the change.

Please keep the following in mind:

• Pull requests should be focused on a single exercise, issue, or change.

• We welcome changes to code style, and wording. Please open a separate PR for these changes if possible.

• Please open an issue before creating a PR that makes significant (breaking) changes to an existing exercise or makes changes across many exercises. It is best to discuss these changes before doing the work.

• Follow the coding standards found in The Elm Style Guide. Please consider running elm-format before submitting a pull request.

• Watch out for trailing spaces, extra blank lines, and spaces in blank lines.

• Each exercise must stand on its own. Do not reference files outside the exercise directory. They will not be included when the user fetches the exercise.

• Exercises should use only the Elm core libraries.

• Please do not add a README or README.md file to the exercise directory. The READMEs are constructed using shared metadata, which lives in the exercism/x-common repository.

• Each exercise should have a test suite, an example solution, a template file for the real implementation and an elm-package.json file with the elm-test and elm-console dependencies. The CI build expects files to be named using the following convention. The example solution should be named ExerciseModuleName.example. The template file should be named ExerciseModuleName.elm. Test file should be named ExerciseModuleNameTest.elm.

• The recommended workflow when working on an exercise is to first create the implementation and test files, ExerciseModuleName.elm and ExerciseModuleNameTest.elm.

  • Test the new exercise directly by running elm-test exercises/exercise_module_name/ExerciseModuleNameTest.elm.

  • Once the implementation of the exercise is complete, move ExerciseModuleName.elm to ExerciseModuleName.example and create the template file.

  • Make sure everything is good to go by running all tests with bin/build.sh.

  • If you have elm-format installed, you can easily check the project by running WITH_FORMAT=true bin/build.sh. If you get diffs on exercises other than the one you are working on, please submit a separate pull request.

• Please do not commit any Elm configuration files or directories inside the exercise, such as elm-stuff. Please include only the standard elm-package.json.

• Test files should use the following format:

port module Main exposing (..)

import Test.Runner.Node exposing (run)
import Json.Encode exposing (Value)
import Test exposing (..)
import Expect


tests : Test
tests =
    describe "Bob"
        [ test "first test" <|
            \() ->
                True
                    |> Expect.equal True
        , test "second test" <|
            \() ->
                False
                    |> Expect.equal False
        ]


main : Program Value
main =
    run emit tests


port emit : ( String, Value ) -> Cmd msg

• All the tests for xElm exercises can be run from the top level of the repo with bin/build.sh. Please run this command before submitting your PR.

• If you are submitting a new exercise, be sure to add it to the appropriate place in the config.json and elm-package.json files. Also, please run bin/fetch-configlet && bin/configlet to ensure the exercise is configured correctly.

License

The MIT License (MIT)

Copyright (c) 2016 Katrina Owen, _@kytrinyx.com

Elm icon

We were unable to find copyright information about the Elm logo, nor information about who designed it. Presumably Evan Czaplicki, creator of the Elm language, also made the logo, and holds copyright. It may also fall within the public domain, since it is a geometric shape. We've adapted the official Elm logo by changing the colors, which we believe falls under "fair use".