elm-get

A command line tool to share Elm libraries. The full catalog of Elm libraries lives at library.elm-lang.org.

Install

cabal install elm-get

This will install the elm-get executable in /home/YOU/.cabal/bin.

Use

The next two sections will cover the basics of using elm-get to install libraries from the catalog and publish your own.

Install Libraries

To install a library run:

elm-get install user/project       # Install latest version
elm-get install user/project 0.1   # Install version 0.1

So if you are interested in the evancz/automaton library for Arrowized FRP, you would install it with:

elm-get install evancz/automaton

elm-get is sandboxed by default, so these commands install the library in the current working directory. This means it is easy for different projects to have different dependencies. To actually use the library in your project, you will need to add it to your elm_dependencies.json file which tells the compiler where to look for extra libraries.

Publish Libraries

Before publishing, look through the Library Design Guidelines. Some key takeaways are:

• Design for a concrete use case
• Always give functions human readable names
• Avoid gratuitous abstraction
• Use semantic versioning

After looking through the guidelines carefully, flesh out your elm_dependencies.json file to look something like this:

{ "version": "0.1"
, "summary": "experimental library for structuring code, based on Arrowized FRP"
, "description": "This is an experimental library for structuring code. It is based on Arrowized FRP, which aimed to provide an API for higher-order signal graphs. There are many ways to structure code though, and it is not yet clear when AFRP is a superior method. So this library is meant to explore the basics of AFRP and find cases where it is a really good fit."
, "license": "BSD3"
, "repository": "https://github.com/evancz/automaton.git"
, "exposed-modules": ["Automaton"]
, "elm-version": "0.10.1"
, "dependencies":{}
}

You can also use command elm-get init for initializing basic elm_dependencies.json in console interactively.

A couple important notes for filling in these fields for your project are:

• Keep the summary under 80 characters.
• Make the description a useful outline of the library. It should cover the problems solved by the library, indicate any limitations, and point to related resources that might be helpful. The goal is for someone to be able to quickly assess if the library will suit their goals.
• The recommended license is BSD3, but of course, you can use whatever license you want.
• The exposed-modules are the subset of modules that people can use when they install your library. Use this to stop internal details from polluting your API and cluttering the docs with modules that are not meant for users.
• For now, you cannot publish libraries with dependencies on community libraries. It is the highest priority for this project to lift this restriction while ensuring that dependency management does not become a hellish nightmare.

Once that is all done, use git to tag the specific commit you want to release with an appropriate version number. This should match the version listed in elm_dependencies.json. Finally, you can publish your library with:

elm-get publish