Windows support

[mrmurphy]

We could get windows support one of two ways:

• Windows users could use esy as their package manager instead of (or alongside?) NPM and install this package from source, then build the PPX themselves. That's a bummer for them though.
• Someone could contribute a change that moves the build pipeline for this repo from Travis to Github Actions and adds a Windows build and artifact.

Does this seem like a good first issue?

[ryb73]

Yeah, it'd be nice for the ppx to work the same for Windows users as it does for Mac and Linux. I've been wanting to get my Windows machine working so I can look at this but haven't gotten around to it. It'd be great to have someone work on it!

Re: github actions vs travis: I haven't looked closely at github actions yet; does it provide similar functionality to travis? If I remember correctly Travis does support Windows but I was having trouble getting it working, which is why I only included Mac and Linux. I'd be interested in exploring GitHub Actions though.

[TheSpyder]

What would be needed to contribute this? I'm starting to evaluate decco for a project but we run CI tests on Windows which means we need to be able to compile on Windows. I might be able to allocate some time to fixing this.

Would you prefer Travis for windows or github actions (which yes are similar to Travis)?

[TheSpyder]

I made some attempt to build on windows, initial failures were solved by using a newer version of OCaml. In the end I couldn't get past a mingw requirement. Even if I can get that working, it will really only be useful for validating the executable works. This isn't something I would know how to set up on travis or github actions.

Other projects I know that build with esy and offer windows builds all use azure pipelines, which are free for open source, so that's where I will focus my efforts: https://github.com/esy-ocaml/esy-ci-scripts

[TheSpyder]

SUCCESS! It took a lot of wrangling, but I have a passing build with binaries for linux, mac and windows: https://thespyder.visualstudio.com/Decco%20Builds/_build/results?buildId=29&view=artifacts&type=publishedArtifacts

The individual binaries are published by their respective builds, and then they are all brought together in the npm-package artifact. That could be downloaded as a zip and published as-is (in fact I just published it to my company's internal registry while I wait for help with what to do next).

As a part of this I built a ppx.cmd file to make it work with the --as-ppx command line on windows, and I have tested it on mac / windows / linux. https://github.com/TheSpyder/decco

[ryb73]

That's awesome, thanks @TheSpyder! Would you be able to do a pull request? What are the missing links we need to figure out in order to incorporate it?

[TheSpyder]

There are a few things missing:

• making sure it works on a variety of machines (I just realised I went with macOS-latest so the mac binary probably requires 10.15)
• an azure pipelines project owned by you (I deleted the travis config, but an interim broken state is probably ok since the project doesn't release very often)
• figuring out how to release and publish. Looking at the Travis config, there seems to be mechanisms in place to load an API key to publish to NPM? I assume Azure has the same thing. Azure has the concept of deployment approval gates, so the job can always include a "publish this build" button for every commit that is only activated when necessary.

[TheSpyder]

Now that Travis has windows support, could you try enabling that and see if it works? I can then just PR my runtime scripts to make decco function on windows.

[TheSpyder]

I didn't realise pull requests are run on travis - I can just do that myself and see if it works.