Make stack-ide receive a path where the correct ide-backend-server is installed

[jcpetruzza]

NB. See this pull request, which would first need to be applied to stack-ide.

This PR would be a step into having stack provide the appropriate version of ide-backend-server to each project where stack-ide is used.

What the patch does is simply make stack-ide look for ide-backend-server and ide-backend-exe-cabal in the bin directory of the local and snapshot databases, respectively. If, for every project, one can then persuade stack to build ide-backend-server and ide-backend in addition to the project packages, then one gets the right ghc-version of ide-backend-server for free. At the moment, I achieve this rather crudely by adding the following package entry in the stack.yaml file of every project I want to work on:

- location:
    git: [email protected]:fpco/ide-backend.git
    commit: 329e7670388428709158d33b3e74959671afc345
  subdirs:
  - ide-backend-common
  - ide-backend
  - ide-backend-server

I imagine the stack.yaml format being then extended to allow for a non-project config option that would roughly say: "when building a project for development, also build these packages". That way one could put an entry for ide-backend-server in ~/.stack/stack.yaml and forget about it (it would be also handy to include other "ide tools" there, such as hlint, HaRe, hindent, etc.). Does a setting like that make sense to you?

Anyway, already with the crude version I'm now using, my experience with the Sublime plugin (https://github.com/lukexi/stack-ide-sublime) has improved quite a bit: I just need to remember to paste the above package entry the first time I work on a project, rebuild and everything then just works (if I switch resolvers, change versions of ghc, etc., I just need to restart Sublime).

[mgsloan]

Looks good to me, thanks!

I imagine the stack.yaml format being then extended to allow for a non-project config option that would roughly say: "when building a project for development, also build these packages".

I've also wanted such a thing in the past, but I'm not sure if its necessary. The current way to install such dev dependencies is to run stack install ide-backend ide-backend-server stack-ide. Is this good enough?

[rvion]

In my opinion, no, the current way of installing stack ide (stack install ide-backend ide-backend-server stack-ide) is not really good. There is too much one needs to know to get up and running, and switching projects using differrents snapshots makes it even harder. It's not really user friendly, and I think it goes against the plug and play principle of stack. I saw newcomers fail to use stack ide with sublime plugin, and myself had troubles

[mgsloan]

Indeed, stack ide is still experimental and in development. ide-backend was originally designed for a very different usecase (running on the server, for FPHC), and is still in transition towards being easily used for local development. Now, ide-backend is very powerful and stack-ide is very promising, but there's still more to do before they work well for local development.

It's not really user friendly, and I think it goes against the plug and play principle of stack.

True. Very recently I opened up an issue about having stack manage this - #662. I think I meant to link that from my comment but forgot to. It would be great to have the IDE side of things as streamlined as the other things, and it's certainly true that we're not there yet. Soon, hopefully! Help is appreciated!

[rvion]

That's making me happy :)