Packaging a standalone haskell script in nixpkgs

DamienCassou · September 25, 2021, 3:45pm

Hi,

I would like to package this Haskell script which isn’t on nixpkgs. That script is part of the hledger git repository which is part of nixpkgs.

What do you think I should do?

Thank you

maralorn · September 25, 2021, 10:20pm

Hi Damien,

while hledger is part of nixpkgs the hledger git repo is referenced nowhere, because we get hledger from the hackage tarball. I assume your script is not included there.

If your script is really only one file, I would recommend you to use a combination of fetchurl (on the direct raw github url) and pkgs.writers.writeHaskell(Bin). See:

github.com

NixOS/nixpkgs/blob/77bda0504d452374cb0268d3e727c5149894429f/pkgs/build-support/writers/default.nix#L125


      
          
          
# writeHaskell takes a name, an attrset with libraries and haskell version (both optional)
          # and some haskell source code and returns an executable.
          #
          # Example:
          #   writeHaskell "missiles" { libraries = [ pkgs.haskellPackages.acme-missiles ]; } ''
          #     import Acme.Missiles
          #
          #     main = launchMissiles
          #   '';
          writeHaskell = name: {
            libraries ? [],
            ghc ? pkgs.ghc,
            ghcArgs ? [],
            strip ? true
          }:
            makeBinWriter {
              compileScript = ''
                cp $contentPath tmp.hs
                ${ghc.withPackages (_: libraries )}/bin/ghc ${lib.escapeShellArgs ghcArgs} tmp.hs
                mv tmp $out

If writeHaskell or writeHaskellBin doesnt work for you a pkgs.runCommandusing aghc.withPackages` would probably be the more flexible version.

Hope that helps.

DamienCassou · September 26, 2021, 1:15pm

thank you very much for your suggestion. I created a nixpkgs PR out of it.