Create hls-plugin-api and move plugins to exe

[jneira]

• This is a initial step to acomplish Project architecture to support plugins #164. There @alanz proposed:

I propose the we split hls up

• a slimmed-down core, that basically corresponds to the plugins built into ghcide.
• an API package that can be used by plugin authors to write plugins for use in hls. The corresponds to the hie-plugin-api as originally envisaged.
• a fat package that depends on the core, the api, and all known plugins at this time, and provides an exe depending on them.

The second one would be the hls-plugin-api and the second one the exe component in this pr.

Not sure about:

• the place of actual plugins: maybe the folder could be named builtin instead default?
• should ghcide be in the api or with the rest of plugins?

[pepeiborra]

Maybe add a defaultMain function to hls-plugin-api with the type below, and redefine exe/Main.hs with it?

defaultMain :: [PluginDescriptor] -> IO ()

[pepeiborra]

This is great! Definitely a step in the right direction. Eventually we can move the current plugins into separate packages too, as needed.

[jneira]

Maybe add a defaultMain function to hls-plugin-api with the type below, and redefine exe/Main.hs with it?

defaultMain :: [PluginDescriptor] -> IO ()

Mmm i like to put the main logic in the library like f.e. dhall, if it does not introduce extraneous dependencies.
A drawback could be that, if hls-plugin-api ends up in hackage, you have to make uploads and version bumps for executable related things.

[jneira]

ci nix build failed with:

plugins/default/src/Ide/Plugin/Fourmolu.hs:75:11: error:
    Not in scope: `cfgPrinterOpts'
   |
75 |         , cfgPrinterOpts = printerOpts
   |           ^^^^^^^^^^^^^^
cabal: Failed to build exe:haskell-language-server from
haskell-language-server-0.4.0.0 (which is required by test:func-test from
haskell-language-server-0.4.0.0).

🤔

[pepeiborra]

ci nix build failed with:

plugins/default/src/Ide/Plugin/Fourmolu.hs:75:11: error:
    Not in scope: `cfgPrinterOpts'
   |
75 |         , cfgPrinterOpts = printerOpts
   |           ^^^^^^^^^^^^^^
cabal: Failed to build exe:haskell-language-server from
haskell-language-server-0.4.0.0 (which is required by test:func-test from
haskell-language-server-0.4.0.0).

🤔

Nix uses cabal build, so that error is probably incorrect version bounds for fourmulu. Not sure why it came up on this change, maybe it's broken in master too?

[Ailrun]

Great! I had planned to do this but couldn't find an enough time slot...
Thank you for extracting plugin API!

[jneira]

@alanz @pepeiborra i dont feel hls-plugin-api is the best place to put the defaultMain, what do you think in keep the package main lib and put it (with Ide.Version and Arguments) there? We have to maintain one more component (although already existing in master) but it would have a better separation of concerns.

[pepeiborra]

@alanz @pepeiborra i dont feel hls-plugin-api is the best place to put the defaultMain, what do you think in keep the package main lib and put it (with Ide.Version and Arguments) there? We have to maintain one more component (although already existing in master) but it would have a better separation of concerns.

That sounds fine to me!

[alanz]

I agree. The hls-plugin-api should be the thing that tool writers use to create a plugin that is compatible with hls, and has nothing to do with running it.

So in future I would imagine a person writing say a formatter and including a plugin descriptor directly, and the formatter depends on hls-plugin-api.

[georgefst]

Nix uses cabal build, so that error is probably incorrect version bounds for fourmulu. Not sure why it came up on this change, maybe it's broken in master too?

The log says it's building fourmolu-0.0.6.0. The ^>= 0.1 bound is in haskell-language-server.cabal for a reason, and this PR appears to have accidentally removed it. This looks to be the case for several other libs as well.

[jneira]

The log says it's building fourmolu-0.0.6.0. The ^>= 0.1 bound is in haskell-language-server.cabal for a reason, and this PR appears to have accidentally removed it. This looks to be the case for several other libs as well.

Oops, i forgot to put them when moving the deps around, thanks!

[jneira]

Ok, the executable modules are in the lib now and ci is happy (thanks again @georgefst)

[jneira]

Rebased, i hope this could be merged asap, cause it will likely be in conflict with any other commit, as it shuffles almost all modules in the project

[alanz]

LGTM