Stream: haskell-flake

Topic: ✔ Using non-haskell dependencies

view this post on Zulip Shivaraj B H (Nov 28 2024 at 12:15):

Haven’t used pkgconfig-depends before, doesn’t using extra-libraries work?

view this post on Zulip Shivaraj B H (Nov 28 2024 at 12:19):

here’s an example cabal and nix configuration respectively, might be helpful:
https://github.com/juspay/superposition/blob/5b8410ea776a1758309b927ff2ab8b5370774431/clients/haskell/hs-exp-client/hs-exp-client.cabal#L114-L115
https://github.com/juspay/superposition/blob/5b8410ea776a1758309b927ff2ab8b5370774431/clients/haskell/default.nix#L8

view this post on Zulip Perigord (Nov 28 2024 at 12:30):

yeah just addinglibavcodec.custom = _: pkgs.ffmpeg.lib; to settings worked

view this post on Zulip Notification Bot (Nov 28 2024 at 12:30):

Perigord has marked this topic as resolved.

view this post on Zulip Daniel Herrera Rendón (Jan 06 2025 at 13:16):

Hello cool nix people : )

I'm trying to use a non-haskell dependency and failing. To make it simpler I'm using pkgs.cowsay as the executable I want to run on my haskell code with:

cowsay :: IO String
cowsay = do
  (_, mhout, _, _) <- createProcess (shell ("cowsay hola")) { std_out = CreatePipe }
  case mhout of
    Just hout -> hGetContents hout
    Nothing -> pure "mhout failed"

I've added to the corresponding cabal executable stanza build-tools: cowsay (also tried with extra-libraries but that just complained of not being a good C library)

This is my whole flake:

{
  inputs = {
    nixpkgs.url = "github:nixos/nixpkgs";
    flake-parts.url = "github:hercules-ci/flake-parts";
    haskell-flake.url = "github:srid/haskell-flake";
    hvm.url = "github:hhefesto/HVM";
    flake-compat = {
      url = "github:edolstra/flake-compat";
      flake = false;
    };
  };

  outputs = inputs@{ self, nixpkgs, flake-compat, hvm, flake-parts, haskell-flake, ... }:
    flake-parts.lib.mkFlake { inherit inputs; } {
      systems = [ "x86_64-linux" "aarch64-linux" ];
      imports = [ inputs.haskell-flake.flakeModule ];
      perSystem = { self', system, pkgs, ... }: {
        haskellProjects.default = {
          basePackages = pkgs.haskell.packages.ghc92;
          settings = {
            cowsay.custom = _: pkgs.cowsay;
            telomare = {
              extraBuildDepends = [ pkgs.cowsay
                                  ];
            };
          };
          devShell = {
            enable = true;
          };
      };
      packages.default = self'.packages.telomare;
      apps.default = {
        type = "app";
        program = self.packages.${system}.telomare + "/bin/telomare";
      };

      apps.repl = {
        type = "app";
        program = self.packages.${system}.telomare + "/bin/telomare-repl";
      };
    };
  };
}

n.b. in settings I've added cowsay.custom = _: pkgs.cowsay; and also triedsettings.telomare.extraBuildDepends = [ pkgs.cowsay ];

To test it you just have to nix run . for the flake-parts branch in https://github.com/hhefesto/stand-in-language/tree/flake-parts

Am I doing something wrong?

view this post on Zulip Daniel Herrera Rendón (Jan 06 2025 at 13:25):

Forgot to add the error:

$ nix run .
/bin/sh: line 1: cowsay: command not found

Last updated: Jan 13 2025 at 23:14 UTC