Combining cookiecutter's Haskell template and hie

Help
1

I recently read this thread and set up a new Haskell/Nix project using the cookie cutter template. Now I’d like to add haskell-ide-engine “support” for it. I tried following the instructions to install hie globally and set it to build for ghc865 via…

    ((import (fetchTarball "https://github.com/infinisil/all-hies/tarball/master") {}).selection { selector = p: { inherit (p) ghc865; }; })

…in my configuration.nix below systemPackages.

In my project, I then set the same nixpkgs rev as hie uses (just to be sure) and set compiler to ghc865. My default.nix is here. However, Nix complains about: attribute 'ghc865' missing.

Did something change with regards to the Haskell package structure that causes this?

2

The revision of Nixpkgs you pinned your project at is fairly old and doesn’t actually include GHC 8.6.5, only 8.6.4. Also IIRC all-hies uses a Nixpkgs pin per compiler version so perhaps you picked a wrong revision?

3

Ahh, thanks for the advice! So I guess the specific pin is inside the nixpkgsForGhc subfolder? I’ll try pinning to 882 and see if that works.

4

Indeed, although so long as the compiler version of your project and hie match I don’t think it should be necessary to pin both at exact same nixpkgs revision. Though I believe hie will pull in GHC in its own closure so you may end up with some extra duplication / used storage but I don’t think it shold cause any issues.