Getting started with nix and haskell

config.nix

{ pkgs }:

{
    allowBroken = true;
    allowUnfree = true;

    haskellPackageOverrides = self : super : (let inherit (pkgs.haskell-ng) lib; in {
            ghc-mod = lib.overrideCabal super.ghc-mod (oldAttrs: {
                src = pkgs.fetchgit {
                url = https://github.com/kazu-yamamoto/ghc-mod;
                rev = "247e4e0e7616fe1fecc68fdcf80d6249ac4cee4f";
                sha256 = "2a23271d0e6907351a246f095040ba18c3ab6bf1cba08a14338d701defa55474";
                };
                buildDepends = oldAttrs.buildDepends ++ [ self.cabal-helper self.cereal ];
                patchPhase = "${pkgs.gnused}/bin/sed -i 's/Version:\ *0/Version:5.0.1.1/' ghc-mod.cabal";
                });

            cabal-helper = lib.overrideCabal super.cabal-helper (oldAttrs: {
                version = "0.3.2.0";
                sha256 = "06igjmr0n8418wid1pr74cgvlsmwni7ar72g9bddivlbxax1pfli";
                });

                halive = self.callPackage ./haskell/halive {};
            });


    packageOverrides = pkgs : rec {

        devTools = with pkgs; buildEnv {
            name = "devTools";
            paths = [
                neovim
                zeal
                ];
        };


        ghcEnv = pkgs.haskellngPackages.ghcWithPackages (p : with p; [
                alex
                cabal2nix
                cabal-install
                codex
                ghc
                ghcid
                ghc-mod
                halive
                hasktags
                hdevtools
                hlint
                happy
                hoogle
                hspec
                purescript
                ]);

        nodeEnv = with pkgs; buildEnv {
            name = "node";
            paths = [
                nodejs
                ] ++ (with nodePackages; [
                        npm2nix
                        ]);
        };

    };
}

functions.sh

nix-search(){ nix-env -qa \* -P | grep -i "$1"; }                                                                                                                                                            
nsh() { nix-shell -E 'with (import <nixpkgs> {}).pkgs; (haskellngPackages.callPackage ./default.nix {}).env' "$@" }                                                                                          

getting started with nixos

install nix

Get it from nixos.org/nix - After installation you should have nix-env and various others nix commands in your path.

Get nixpkgs master

clone nixpkgs : https://github.com/NixOS/nixpkgs - This is the bleeding edge. I did my setup with nixpkgs but it should work the same way if you stick to the 14.12 channel. You decide. If you want to use master then the nix-channel command is basically meaningless to you. You update your packages (nix expressions) by pulling the nixpkgs repo. Otherwise you use nix-channel --update to update. In order to tell nix to use binary caches (to prevent compiling everything) save the nix.conf file at /etc/nix/nix.conf.

If you want to use 14.12 do a nix-channel --update right now and skip the next paragraph.

Remove the link in the $(HOME)/.nix-defexpr directory and create a link to your nixpkgs clone: ln -s /path/to/nixpkgs nixpkgs

Install Tools

Now its time to install ghc and whatever else you want to use for your haskell hacking. First copy the config.nix file to $(HOME)/.nixpkgs. Then use ghc-env -i ghcEnv to install everything listed in the ghcEnv environment. Of course you should first remove anything you are not interested in.