Integrate psa into Spago

[f-f]

Since the upcoming Spago will be in PureScript, we now have the occasion of integrating psa directly as a library, which is strictly better than the current situation of shelling out to an external executable.

[JordanMartinez]

I'm going to work on this, but this is low priority.

[JordanMartinez]

Here's a few questions that came to mind as I was looking at this:

• Is the codebase of purescript-psa-utils going to be folded into spago in its entirety? Or are we just going to depend on that as another dependency? I'd prefer the former because there's less dependency management than the latter (e.g. "If I change X in purescript-psa-utils, does it cause issues in spago?"). However, if one wanted to implement another package manager besides spago, such an author would likely want to reuse the psa libraries to implement similar features, at least until this functionality is folded into the compiler itself.
  • Depending on the above answer, purescript-psa and purescript-psa-utils have either open issues/PRs. When integrating it into this codebase, do we want to account for those issues/PRs as well? One that strikes me in particular is Add support for finer grained censoring of user defined warnings natefaubion/purescript-psa-utils#10, which would have made the Semigroup/Map warning less annoying.

[natefaubion]

I have no intention of making additions to psa.

[arrowd]

A bit of offtopic, but what is rationale behind rewriting Spago in PureScript? This will make packaging it harder for downstream packagers.

[f-f]

@arrowd I have detailed a bit about it here, but I'll expand more on it once we announce the first alpha release of the rewrite.
Our main packaging method is npm, which will benefit from the switch. Is there any particular downstream packager you are concerned about?

[arrowd]

I am that downstream packager - I make ports for FreeBSD. Wehave nica machinery for Haskell packages that allows us to prefetch all needed deps' sources and build offline. AFAIK, it is not possible for npm.

For purescript-language-server I had to ask @nwolverson to provide self-contained compiled .js files on the releases page.

[f-f]

It sounds like we could reuse that machinery from the language-server repo to achieve the same result here?