Generation of paths.json assumes pakcs

[nevrome]

I learned about the curry language server in the most recent episode of the Haskell Interlude podcast - thank you for developing this!

I managed to set it up with the ecode editor, but ran into an issue with the paths.json file. My understanding is as follows: By default the curry-language-server assumes that pakcs is used as a compiler and calls pakcs cypm deps --language-server to populate the .json file with the relevant paths. I'm using kics2 almost exclusively, though, so this failed. After some digging I realized that I can just call cypm deps --language-server manually, using the cypm executable that comes with kics2 for (seemingly) the same effect.

I was wondering now, why the curry-language-server does not just call cypm here without assuming a specific curry compiler? Wouldn't that be more robust?

[mihanus]

Thanks for reporting this issue! One can set the path to the Curry executable (which has pakcs as default value) but it seems that the user setting is ignored in this case (I just tested it). I'll think about some fix.

[nevrome]

Thank you for looking into this! In the meantime I had some Email contact with another developer involved with this project, and was thus already made aware of the option to set the curryPath. With ecode I was able to set it in the lsp server configuration for curry, and it did work for me:

    {
      "command": "curry-language-server",
      "file_patterns": [
        "%.curry$"
      ],
      "initializationOptions": {
        "curryPath": "/home/clemens/software/kics2-3.5.0-x86_64-linux/bin/kics2"
      },
      "language": "curry",
      "name": "curry-language-server",
      "rootIndicationFileNames": [
        "package.json"
      ],
      "url": "https://github.com/fwcd/curry-language-server"
    }

Only an absolute path will work -- probably the editor does not have access to my user's PATH.

So this makes things a bit easier for me, thank you. I don't have to generate the paths.json file manually any more.

Maybe the log messages could be slightly adjusted, to give some concrete hints for users like me. It should include the information that the curryPath can be set, that this must be done through the LSP interface of the editor (not with a command line argument), and that all of this serves to create a paths.json file with cypm deps --language-server. And that this can also be done manually. I'm happy to propose something, if you agree.

[mihanus]

I fixed this problem by calling cypm directly if the call to pakcs cypm does not work, i.e., the command cypm deps --language-server is executed. If this also does not work, at least a comment is reported (in the log) that one should manually run this command.

I hope this helps.

[nevrome]

Excellent - that is exactly what I was hoping for. Thank you for implementing these changes!

For the sake of completeness: When I now start my editor with a fresh curry project I get the following LSP log messages:

2026-09-14 18:12:19 - NOTICE: Entering project <...>
2026-09-14 18:12:19 - NOTICE: Resolving dependencies automatically since package.json was found...
2026-09-14 18:12:19 - WARNING: Could not update paths.json using command 'pakcs cypm', trying 'cypm' directly...
2026-09-14 18:12:19 - WARNING: Could not update paths.json using command 'cypm'!
2026-09-14 18:12:19 - WARNING: Possible solution: manually run command 'cypm deps --language-server')
2026-09-14 18:12:19 - WARNING: Trying to read paths.json anyway...
2026-09-14 18:12:19 - NOTICE: Reading paths.json...
2026-09-14 18:12:19 - WARNING: Could not read paths.json (Could not read or decode <...>/.curry/language-server/paths.json!), trying fallback resolution of Curry standard libraries by locating the 'pakcs' executable...
2026-09-14 18:12:19 - WARNING: Could not find Curry standard libraries, this might result in 'missing Prelude' errors...

And when I start it from the command line with access to the PATH variable, where I have kics2's cypm available:

2026-09-14 18:20:33 - NOTICE: Entering project <...>
2026-09-14 18:20:33 - NOTICE: Resolving dependencies automatically since package.json was found...
2026-09-14 18:20:33 - WARNING: Could not update paths.json using command 'pakcs cypm', trying 'cypm' directly...
2026-09-14 18:20:33 - NOTICE: Successfully updated paths.json using command 'cypm'!
2026-09-14 18:20:33 - NOTICE: Reading paths.json...
2026-09-14 18:20:33 - NOTICE: Successfully read paths.json: 18 path(s)
2026-09-14 18:20:33 - NOTICE: Searching for sources...