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Help with haskell package that lives in a subdirectory of src

edit: for the solution, see my comment below

I need/want to build aeson and its subproject attoparsec-aeson from source (it's a fork of the "official" aeson), but I'm stuck... can you help out?

The sources of attoparsec-aeson live in a subdirectory of the aeson ones, so I have the sources: 

 nix
    
aeson-src = fetchFromGitHub {
  ...
};

and the "main" aeson library: 

 nix
    
aeson = haskellPackages.mkDerivation {
  pname = "aeson";
  src = aeson-src;
  ...
};

When I get to attoparsec-aeson however I run into a wall: I tried to follow the documentation about sourceRoot: 

 undefined
    
attoparsec-aeson = haskellPackages.mkDerivation {
  pname = "attoparsec-aeson";
  src = aeson-src;
  sourceRoot = "./attoparsec-aeson"; # maybe this should be "${aeson-src}/attoparsec-aeson"?
                                     # (it doesn't work either way)
  ...
};

but I get 

 plaintext
    
 error: function 'anonymous lambda' called with unexpected argument 'sourceRoot'

Did I fail to spot some major blunder (I am nowhere near an expert)? Does sourceRoot not apply to haskellPackages.mkDerivation? What should I do to make it work?

BTW:

IDK if this may cause issues, but the attoparsec-aeson sources include symlinks to files in the "main" attoparsec sources: 

 shell
    
~/git-clone-of-attoparsec-sources $ tree attoparsec-aeson/
attoparsec-aeson/
├── src
│   └── Data
│       └── Aeson
│           ├── Internal
│           │   ├── ByteString.hs -> ../../../../../src/Data/Aeson/Internal/ByteString.hs
│           │   ├── Text.hs -> ../../../../../src/Data/Aeson/Internal/Text.hs
│           │   └── Word8.hs -> ../../../../../src/Data/Aeson/Internal/Word8.hs
│           ├── Parser
│           │   └── Internal.hs
│           └── Parser.hs
├── attoparsec-aeson.cabal
└── LICENSE

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7 comments

  • This may or may not be helpful to you, but I haven’t had to delve into dependency management because I use ‘hix’ to provision and build my Haskell dev environment. I’d highly recommend it. It will simply parse you cabal file and provision all dependencies. I’m hoping such tooling comes to Purescript next because purs-nix is out of date with the new spago).

    Here’s a super simple project where I used it:

    https://github.com/harryprayiv/XY_math

    Ps. I also recommend looking into IOHK’s Haskell tooling and their devshell, which I like to bring into most of my Haskell dev environments.

    • I agree: flakes are great for development (and not only)!

      Unfortunately I still need to build that third party project from source :)
      Maybe I should look into disregarding the whole haskellPackages infrastructure and just build with cabal via a shell script.. IDK if that would be accepted in nixpkgs though :/

      • True! I wonder if the same is true for deriving via cabal2nix.

        • cabal2nix doesn't care about any source-repository-package in cabal.project (I think it doesn't even read that file?).

          In my case, it generated a project that depended on the aeon from nixpkgs (which IIUC in turn comes from hackage) rather than the forked version.

7 comments