Add shell.nix + GH Actions + concatMap function (proposal) ✅

[kutyel]

Hi again! 👋🏻

I noticed this repo did not have any sort of CI so I wanted to propose this one (blatantly copied from https://github.com/turboMaCk/any-dict), it works pretty fast and I think the set up is very quick!

I also felt like proposing to contribute the concatMap function (was surprised to notice today that it is missing in the core module when I tried to use it), but feel free to discard that change if we only want to have a functioning CI pipeline as as result of this PR 😉

[skyqrose]

concatMap has the arguments in the same order as andThen : (a -> Maybe b) -> Maybe a -> Maybe b

Thanks for the CI proposal. That's something I'd been wanting to do, but hadn't really thought much about how to actually do it. I do like nix, and have been looking at finding ways to use it, but given the existing ecosystem around npm, which this repo is already bought into, I think npm will be a more maintainable tool to use for building in ci.

I've made #70, built off the core of this PR. Can you take a look at it and see if there's anything I've missed?

[kutyel]

Right, closing this in favor of #70 😉