On the fly node package inside nix-shell

default.nix

{ pkgs ? import <nixpkgs> {} }: with pkgs;

let
  node2nix = nodePackages.node2nix;
  emmet = stdenv.mkDerivation rec {
    name = "emmet-cli-${version}";
    version = "1.2.0";
    phases = [ "installPhase" ];
    src = builtins.fetchurl {
      url = "https://github.com/Delapouite/emmet-cli/archive/v${version}.tar.gz";
      sha256 = "1vq3c0i5cid2zs5j53v778wj0wdka57nny1jvsaa8adj26mjnw6f";
    };
    installPhase = ''
      mkdir $out;
      tar -xzf $src;
      mv emmet-cli-${version}/* $out;
    '';
  };
in
  mkShell {
    shellHook = ''
      mkdir /tmp/emmet;
      cp -r ${emmet}/* /tmp/emmet;
      pushd /tmp/emmet;
      ${node2nix}/bin/node2nix;
      nix-build -A package
      export PATH=$(pwd)/result/bin:$PATH;
      popd;
    '';
  }