config.nix

{
  packageOverrides = pkgs: rec {
    i3-ws = pkgs.callPackage ./i3-ws.nix {};
  };
}

i3-ws.nix

{ pkgs ? import <nixpkgs> {} }:
let

inherit (pkgs) fetchFromGitHub stdenv;

in
stdenv.mkDerivation {
    name = "i3-ws";
    src = fetchFromGitHub {
        owner = "Enzime";
        repo = "i3-ws";
        rev = "bca34b6b10509088ceac03fb9a1ef27808165ccb";
        sha256 = "1i014hsi80wsaxmdpl8ccwhpvnclkl14w4r0mbci3yqap8a32wgn";
        fetchSubmodules = true;
    };

    buildInputs = with pkgs; [
        i3 jsoncpp libsigcxx
    ];

    nativeBuildInputs = with pkgs; [
        cmake pkgconfig
    ];
}