Elm 0.17, shareable

Package Manager

Elm relies on a package manager to install, share, and distribute libraries and manage dependencies in your projects. To get access to the package manager, you must install the Elm Platform.

On the command line, run elm-package or elm package. Without an argument, it will return help about options available.

elm-package.json

Like many package managers, the elm package managers stores all data about installed dependencies in a json file, elm-package.json.

File: elm-package.json

{
    "version": "1.0.0",
    "summary": "helpful summary of your project, less than 80 characters",
    "repository": "https://github.com/user/project.git",
    "license": "BSD3",
    "source-directories": [
        "."
    ],
    "exposed-modules": [],
    "dependencies": {
        "elm-lang/core": "4.0.0 <= v < 5.0.0",
        "elm-lang/html": "1.0.0 <= v < 2.0.0",
        "mgold/elm-date-format": "1.1.4 <= v < 2.0.0"
    },
    "elm-version": "0.17.0 <= v < 0.18.0"
}

If you only have one file, it's fine to keep it in the top level folder. Otherwise, you should create a src folder and keep all source files in there. You'll need edit elm-package.json to read "source-directories": [ "src" ], (don't forget the comma; elm package doesn't give a helpful error on invalid JSON).

In elm-package.json, A package will export at least one module in the "exposed-modules" field.

elm-stuff folder

All dependencies will be installed in a folder named elm-stuff. It is typically a good idea to add it to your .gitignore file when publishing elm code on github.

elm package install

The most common use of elm package is to install dependencies. In the root directory of your project, execute elm-package install [PACKAGE] [VERSION].

-- install the latest version compatible with other packages installed
$ elm package install elm-lang/mouse
-- install a specific version
$ elm-package install elm-lang/mouse 1.0.0

If a call to elm package install results in the installation of new files, the json file will be automatically updated. There is no need to add a '-i' parameter like you would with npm.

All packages are installed in local mode. They are added to elm-stuff/packages folder, in your working directory.

Extra parameters are available. Type elm package install --h for information on them.

elm-package diff

To rapidly check the changes that have been introduced between a version on you local machine and a new release, you can use elm-package diff. This will output all differences between the files.

$ elm-package diff evancz/virtual-dom  2.0.0 2.1.0
Comparing evancz/virtual-dom 2.0.0 to 2.1.0...
This is a MINOR change.

------ Changes to module VirtualDom - MINOR ------

    Added:
        attributeNS : String -> String -> String -> VirtualDom.Property

Searching for Packages

The full catalogue of community libraries is located at package.elm-lang.org.