How to debug hie problems?

[jwiegley]

I'm having some difficulties getting haskell-ide-engine working under Emacs with my Nix configuration. Right now I'm facing this:

hie: <command line>: cannot satisfy -package-id aeson-1.2.4.0-G9AwmJGyHa062BMlqjD9fS
    (use -v for more information)

However, as far as I can tell, this is available in my environment, and cabal is building with this version of the library.

Is there a way to run hie so that I can try to track down where this is coming from? I'm not even sure yet how this is being triggered, since if I just run "hie" on the command-line, it doesn't report any errors, but neither do I know how to simulate whatever Emacs does when I open a Haskell file.

I'm asking here because I don't know what to do next, and I'd love to start using HIE for development. Thanks!

[lukel97]

There are a bunch of flags you can pass to HIE to get some extra information

• --debug will output extra information to stderr
• --vomit will output extra information from ghc-mod to stderr
• -l /log/file will specify a directory to output logs such about requests received and responses received to a certain directory.

Is the project that you're running HIE on a stack project? If so make sure there aren't any dist or new-dist or cabal.project.local or .ghc-environment files lying around that might trick it into using cabal.
I also found that I got that error when the version of HIE doesn't match the resolver that the project uses, i.e. if you're using GHC 8.2.2 then your client should run hie-8.2.2 that was installed via make build

[alanz]

@jwiegley, the best approach for use under nix is to look at https://github.com/domenkozar/hie-nix

[jwiegley]

Yes, that's what I've been using.

[alanz]

Great. Does this mean we can close this issue?

[alanz]

Unless you want to make a PR on the docs, and then close it ... :)

[jwiegley]

I guess the question is: is there a way from the command-line to poke HIE to do what it's going to do when I say, try to lookup an identifier in a file. For example, it's much easier to diagnose hdevtools problem, because I can run hdevtools check ... at the command-line to at least take Emacs out of the picture until the CLI is working. But with HIE, it seems that once I run it I enter into some kind of event loop, but I don't know what events to send it. There are too many layers between Emacs and HIE for me to understand what's triggering the error that I see.

[alanz]

This is unfortunately a byproduct on focusing on LSP, and deprecating the other methods (which were always pretty iffy anyway, especially the console).

Hopefully the GSOC work @bubba is doing will make this easier in future.

[jwiegley]

Do you know of any CLI that can fabricate the kinds of events Emacs is probably sending?

[alanz]

Not at the moment.

But as I said, most likely option is going to be https://github.com/Bubba/haskell-lsp-test

[cah6]

@jwiegley I ran into the same thing in my local setup (with Nix). I finally found NixOS/nixpkgs#46453, though setting those env variables manually still didn't fix my editor integration. Maybe the other changes in that PR fix it, or maybe it's something else...still investigating.

[alanz]

I guess we should update the README for this, then close it.