Elm Env

Elm Env provides an easy way to run an Elm environment from its Haskell source, inside a Docker container. Cabal can be difficult to get installed, especially because certain versions of Elm require different Haskell versions. Elm-platform provides a useful way to install different versions of Elm from source. However, if you just want to tinker with the source code for a bit of Friday fun, and don't want it to mess with the current version/installation of Elm on your computer, elm-env is for you!

Easy Install

Provided you already have Docker installed, all you need to do is run:

docker run -it breezykermo/elm-env

After docker has fetched the image from Docker Hub, your container should start and you will be inside a Linux bash shell in a Docker container, with the Elm environment 0.18 code in the Elm-Package directory.

Using other versions of Elm

To install other versions of Elm, run the BuildFromSource.hs script provided:

runhaskell BuildFromSource.hs <version-no>

where <version-no> is the version you want to install. The script will complain if you try with a version that doesn't exist.

Using Elm Env for Development

Unless your preferred text editor is nano, you'll want to map the source files in the Docker container to your local as volumes, so that you can view and edit them through a different text editor.

To do this, copy the files from inside a running elm-env container to an outer directory, as src:

docker cp $(CONTAINER_ID):/Elm-Package/Elm-Platform . && mv Elm-Platform src

replacing $(CONTAINER_ID) with your elm-env instance's container ID.

If you have Docker Compose, You can then run elm-env with these files as volumes easily through the Docker-Compose file provided:

docker-compose run --rm elm-env

Alternatively, you can run the container with the src directory as a volume directly through this command:

docker start -i -v src:/Elm-Package/Elm-Platform $(CONTAINER_ID)

Installing Elm versions from custom source repos

You can easily build custom Docker images with your own forks of the various Elm codebases, by modifying BuildFromSource.hs. The Dockerfile simply runs the BuildFromSource.hs script and puts what is generated in an image.