How to use the output of cabal2nix in a flake?

[malikwirin]

Since Zephyr is marked as broken in nixpkgs because its dependencies are no longer available in nixpkgs. Before bumping the dependencies I was looking into solving the issue of using Nix as build tool on the Zephyr repo before bumping its dependencies. When using the the cabal2nix tool inside the repo I get the following output:

{ mkDerivation, aeson, ansi-terminal, ansi-wl-pprint, async, base
, boxes, bytestring, containers, directory, filepath, formatting
, Glob, hspec, hspec-core, HUnit, language-javascript, lib, mtl
, optparse-applicative, process, purescript, QuickCheck, safe, text
, transformers, unordered-containers, utf8-string
}:
mkDerivation {
  pname = "zephyr";
  version = "0.5.3";
  src = ./.;
  isLibrary = true;
  isExecutable = true;
  libraryHaskellDepends = [
    aeson ansi-terminal base boxes containers formatting
    language-javascript mtl purescript safe text unordered-containers
  ];
  executableHaskellDepends = [
    aeson ansi-terminal ansi-wl-pprint async base bytestring containers
    directory filepath formatting Glob language-javascript mtl
    optparse-applicative purescript text transformers utf8-string
  ];
  testHaskellDepends = [
    aeson base containers directory hspec hspec-core HUnit
    language-javascript mtl optparse-applicative process purescript
    QuickCheck text transformers
  ];
  testToolDepends = [ purescript ];
  homepage = "https://github.com/MaybeJustJames/zephyr#readme";
  description = "Zephyr, tree-shaking for the PureScript language";
  license = lib.licenses.mpl20;
  mainProgram = "zephyr";
}

Using it to create the following default.nix

{ pkgs ? import <nixpkgs> { }, ... }:

  let
    mkDerivation = pkgs.stdenv.mkDerivation;
    lib = pkgs.lib;
    haskellPkg = pkgName: pkgs.haskellPackages."${pkgName}";

    aeson = haskellPkg "aeson";
    ansi-terminal = haskellPkg "ansi-terminal";
    ansi-wl-pprint = haskellPkg "ansi-wl-pprint";
    async = haskellPkg "async";
    base = haskellPkg "base";
    boxes = haskellPkg "boxes";
    bytestring = haskellPkg "bytestring_0_12_1_0";
    containers = haskellPkg "containers_0_7";
    directory = haskellPkg "directory_1_3_9_0";
    filepath = haskellPkg "filepath_1_5_3_0";
    formatting = haskellPkg "formatting";
    Glob = haskellPkg "Glob";
    hspec = haskellPkg "hspec";
    hspec-core = haskellPkg "hspec-core";
    HUnit = haskellPkg "HUnit";
    language-javascript = haskellPkg "language-javascript";
    mtl = haskellPkg "mtl_2_3_1";
    optparse-applicative = haskellPkg "optparse-applicative";
    process = haskellPkg "process_1_6_25_0";
    purescript = haskellPkg "purescript";
    QuickCheck = haskellPkg "QuickCheck";
    safe = haskellPkg "safe";
    text = haskellPkg "text_2_1_1";
    transformers = haskellPkg "transformers_0_6_1_2";
    unordered-containers = haskellPkg "unordered-containers";
    utf8-string = haskellPkg "utf8-string";
  in mkDerivation rec {
    name = "zephyr";
    pname = name;
    src = ./.;
    isLibrary = true;
    isExecutable = true;
    libraryHaskellDepends = [
      aeson ansi-terminal base boxes containers formatting language-javascript mtl purescript safe text unordered-containers
    ];
    executableHaskellDepends = [
      aeson ansi-terminal ansi-wl-pprint async base bytestring containers
      directory filepath formatting Glob language-javascript mtl
      optparse-applicative purescript text transformers utf8-string
    ];
    testHaskellDepends = [
      aeson base containers directory hspec hspec-core HUnit
      language-javascript mtl optparse-applicative process purescript
      QuickCheck text transformers
    ];
    testToolDepends = [ purescript ];
    meta = {
      description = "Zephyr, tree-shaking for the PureScript language";
      license = lib.licenses.mpl20;
      homepage = "https://github.com/MaybeJustJames/zephyr";
      maintainers = with pkgs.lib.maintainers; [ malik ];
    };
    hydraPlatforms = lib.platforms.none;
    mainProgram = name;
  }

With the following flake.nix

{
  description = "Flake utils demo";

  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
    flake-utils.url = "github:numtide/flake-utils";
  };

  outputs = { self, nixpkgs, flake-utils }:
    flake-utils.lib.eachDefaultSystem (system:
      let pkgs = nixpkgs.legacyPackages.${system}; in
      {
        packages = rec {
          default = zephyr;
          zephyr = import ./default.nix { inherit pkgs; };
        };
      }
    );
}

When doing nix build . I get the following response:

error: builder for '/nix/store/8flm9jchd4526lda5nq0m8nb2sacq30p-zephyr.drv' failed to produce output path for output 'out' at '/nix/store/8flm9jchd4526lda5nq0m8nb2sacq30p-zephyr.drv.chroot/root/nix/store/bhx8nlfdaw5rlzjv2103p9kp8f0g1rcy-zephyr'

And when doing nix-build I get the following:

this derivation will be built:
  /nix/store/qviyy779xrq20fb8c3d14yq2mjwj9ai0-zephyr.drv
building '/nix/store/qviyy779xrq20fb8c3d14yq2mjwj9ai0-zephyr.drv'...
Running phase: unpackPhase
unpacking source archive /nix/store/mqscmdznjifxaml3704kgx5lnj98mmvy-zephyr
source root is zephyr
Running phase: patchPhase
Running phase: updateAutotoolsGnuConfigScriptsPhase
Running phase: configurePhase
no configure script, doing nothing
Running phase: buildPhase
no Makefile or custom buildPhase, doing nothing
Running phase: installPhase
no Makefile or custom installPhase, doing nothing
Running phase: fixupPhase
error: builder for '/nix/store/qviyy779xrq20fb8c3d14yq2mjwj9ai0-zephyr.drv' failed to produce output path for output 'out' at '/nix/store/qviyy779xrq20fb8c3d14yq2mjwj9ai0-zephyr.drv.chroot/root/nix/store/wk1wyiqn1i4yblqybmx81hvl5m3y6fdh-zephyr'

I am obviously missing something but could not find the relevant documentation.

[malikwirin]

Found the solution
should have used haskellPackages.mkDerivation instead of stdenv.mkDerivation