Question: my install of haskell-language-server + coc + vim only partially working

[fjhheras]

I have a cabal system installed with ghcup. I installed haskell-language-server using cabal v2-run ./install.hs --project-file install/shake.project hls

Installation was sucessful, but it is not detecting the installed packages in my cabal projects, among other problems. The hlint I installed with cabal install hlint detects the cabal installed packages with no problem.

To solve this, I tried to create a hie.yaml file with the following contents: radle: {cabal: {component: "lib:haskell-language-server"}}, but when running haskell-language-server I receive this error:

  Failed to parse result of calling cabal
  
  cabal: Internal error in target matching. It should always be possible to find
  a syntax that's sufficiently qualified to give an unambiguous match. However
  when matching 'lib:haskell-language-server' we found
  lib:haskell-language-server (unknown-component) which does not have an
  unambiguous syntax. The possible syntax and the targets they match are as
  follows:
  'lib:haskell-language-server' which matches lib:haskell-language-server
  (unknown-component), :pkg:lib:lib:lib:file:haskell-language-server
  (unknown-file)

Other things (maybe unrelated) that I was not able to configure with vim+coc were:

• Linting with hlint
• Go to definition

[fendor]

Hi, thank you for your bug report!
Can you explain your project setup? You will, for example, have better results if you use hie on a cabal or stack project.

Your hie.yaml is meant to explain to hls how your project is loaded. In this case you should describe which files belong to which component. In your given hie.yaml file, you define that any files in this project belong to the component lib:haskell-language-server, the library of the project haskell-language-server.
Assuming you are using a cabal project, your component is lib:<name of the cabal file>.
Here is a rough explanation of this syntax: https://cabal.readthedocs.io/en/latest/cabal-commands.html#cabal-v2-build

[fjhheras]

I am a Haskell beginner, and this is a repo where I am going through the exercises in a book:

https://github.com/fjhheras/haskellbook_exercises

My intention was to create a common cabal project for all chapters, and then call each exrcise file individually using cabal exec -- runghc chapter17/identity.hs for example (scripts of previous chapters are not working with this new system yet). Therefore I did not configure anything in the cabal file, except for dependencies.

[fendor]

That projects looks complicated to configure correctly... We will need a full cabal project, e.g. each file must be possible to open with cabal. If you use a big cabal project, you will probably need a cabal.project file.
We can try too help you set up hls for it, once you managed to create a cabal project for each chapter.

[Avi-D-coder]

Once you have a cabal.project, https://github.com/Avi-D-coder/implicit-hie should be able to generate a correct hie.yaml file.

What's your motive for wanting all the chapters to be in one cabal project?
Why not just treat each chapter as a self-contained cabal package? If cabal build succeeds in a chapter, just run gen-hie > hie.yaml in each chapter.

[fjhheras]

Hi, thank you for your help. I changed the structure so now I have a cabal project for each chapter. The way I did it needs 6 extra lines for each executable (e.g. https://github.com/fjhheras/haskellbook_exercises/blob/master/chapter17/chapter17.cabal), I wonder if there is a better way

With the new structure, a haskell-language-server installation works, but still does not recognise the cabal project dependencies (In comparison, a haskell-ide-engine installation now works perfectly, and even linting is working).

For haskell-language-server to work, as @Avi-D-coder proposed, I installed gen-hie and generated the following hie.yaml file:

cradle:
  cabal:
    - path: "./identity.hs"
      component: "chapter17:exe:identity"

    - path: "./listapplicative.hs"
      component: "chapter17:exe:listapplicative"

    - path: "./lookups.hs"
      component: "chapter17:exe:lookups"

    - path: "./ziplist.hs"
      component: "chapter17:exe:ziplist"

Once placed, haskell-language-server-wrapper is giving me the following errors:

Program error: Failed to load interface for ‘Main’no unit id matching ‘main’ was found

and

  Multi Cradle: No prefixes matched
  pwd: /home/user/Documents/haskell/haskellbook_exercises/chapter17
  filepath: /home/user/Documents/haskell/haskellbook_exercises/chapter17/Setup.hs
  prefixes:
  ("./identity.hs",Cabal {component = Just "chapter17:exe:identity"})
  ("./listapplicative.hs",Cabal {component = Just "chapter17:exe:listapplicative"})
  ("./lookups.hs",Cabal {component = Just "chapter17:exe:lookups"})
  ("./ziplist.hs",Cabal {component = Just "chapter17:exe:ziplist"})
Files that failed:
[INFO] finish: User TypeCheck (took 0.05s)
 * /home/user/Documents/haskell/haskellbook_exercises/chapter17/Setup.hs
 * /home/user/Documents/haskell/haskellbook_exercises/chapter17/ziplist.hs

[oblitum]

@fjhheras have you checked coc wiki about how to install HLS? I'm using binaries provided by @bubba without issues.

[jneira]

@fjhheras Setup.hs is known to fail and ziplist.hs seems to has something different to others (that work). It seems it fails due to #204 so adding a module Main where header would workaround it.

[jneira]

• hlint support is not available (although it will be soon)
• afaik the errors are covered by other issues

So i would close it if you agree, feel free to reopen

[fjhheras]

OK, no worries.