ishiy1993 / canos

cabal's plan.json to nix overlay scripts

canos

cabal's plan.json to nix overlay scripts

Note

This project is experimental and inspired by stacklock2nix.

The scripts of canos depend cabal2nix command and jq command. And this project does not use haskell.nix.

Usage

1. Add canos to the inputs of flake.nix.

{
  description = "...";
  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-22.11";
    flake-utils.url = "github:numtide/flake-utils";
    canos.url = "github:ishiy1993/canos";
    canos.inputs.nixpkgs.follows = "nixpkgs";
    canos.inputs.flake-utils.follows = "flake-utils";
  };
  outputs = { self, nixpkgs, flake-utils, canos }:
    flake-utils.lib.eachDefaultSystem (system:
      let
          pkgs = import nixpkgs { inherit system; };
          hsPkgs = pkgs.haskell.packages.ghc902;
      in
      {
        devShells.default = pkgs.mkShell {
          buildInputs = [
            hsPkgs.ghc
            hsPkgs.cabal-install
            hsPkgs.haskell-language-server

            pkgs.zlib
            canos.packages.${system}.canos-global
            canos.packages.${system}.canos-local
          ];
        };
      }
    );
}

2. Generate nix/ by canos-global and canos-local in nix develop.

$ nix develop -c $SHELL
$ cabal build
$ canos-global
$ canos-local
$ exa --tree nix
nix
├── generated
│  ├── aeson.nix
│  ├── ...
│  └── zlib.nix
├── your-pkg-name.nix
├── haskell-overlay-global.nix
└── haskell-overlay-local.nix
$ git add nix
$ git commit

3. Use overlays in flake.nix and build by nix build '.#your-pkg-name'.

    let
        pkgs = import nixpkgs { inherit system; };
        hsPkgs = pkgs.haskell.packages.ghc902;
        hsCustomPkgs = hsPkgs.override (old: {
          overrides = pkgs.lib.composeManyExtensions [
            (import ./nix/haskell-overlay-local.nix {
              inherit (pkgs.haskell.lib) overrideCabal;
            })
            (import ./nix/haskell-overlay-global.nix {
              inherit (pkgs.haskell.lib) overrideCabal;
              attrs = {
                splitmix = { testu01 = null; };
                zlib = { inherit (pkgs) zlib; };
              };
            })
            (old.overrides or (final: prev: { }))
          ];
        });
    in
    {
      packages.your-pkg-name = hsCustomPkgs.your-pkg-name;
    }