Add Dockerfile for building

[nightscape]

Hi @edwinb,

here is a Dockerfile to simplify the build process.
I've yet to make the corresponding additions to the README, and it would be great to also publish this to Dockerhub for people to tinker around with it 😃
If you want, you can try it out in the mean time by running

docker build -t blodwen .
docker run -it blodwen

on a machine with Docker.

[nightscape]

I added a small section in the README, from my side this is good to merge.
Another great thing would be to add an automated build to Docker Hub.
That way, users would not have to build the image by themselves, but could just use the pre-built one.
@edwinb do you already have an account on Docker Hub, is this one maybe yours?
https://hub.docker.com/r/edwinb/
Here are the steps to create such an automated build, I would also be happy to help if anything goes wrong:
https://docs.docker.com/docker-hub/builds/#create-an-automated-build

In theory, I could also create this on my Docker Hub account, but it would be more trustworthy if it were yours 😉

[nightscape]

@edwinb any thoughts on this?
For the impatient: I pushed my Blowden Docker image to https://hub.docker.com/r/nightscape/blodwen/

[edwinb]

Hi, thanks for doing this!
My main worry about it is that I only know slightly more than nothing about Docker (that user is unlikely to be me unless I set it up last year and forgot about it which I'm sure I didn't!) and realistically I need to be able to maintain all of the different build and distribution mechanisms that will be part of this repository. At this stage, it's still possible that things might change rapidly enough that I break the docker build and I can't promise to be able to fix it if I do.

If it's clear that it's experimental, comes with no promises, no support from me, and that it might break at any moment, then perhaps it's still good to include here. At the moment I don't really have the time to learn the necessary stuff to keep it up to date though, no matter how easy it might really be. I will learn one day once Blodwen gets a bit more stable, at least.

[bbarker]

Hello - just a suggestion I learned from another language repo: Maybe it would make sense to have a contrib directory for such things, with possible symbolic links going into contrib. e.g, ROOT/Dockerfile -> ROOT/contrib/Dockerfile OR ROOT/contrib//Dockerfile. Same idea for the nix stuff, etc. The other language repo is https://github.com/githwxi/ATS-Xanadu - you can see how e.g. nix and travis-ci are using symbolic links.

[zaoqi]

This branch has conflicts that must be resolved