default.nix

{ config, pkgs, lib, ... }:

with import <home-manager/modules/lib/dag.nix> { inherit lib; };

let
  version = "0.9.57";

  release = pkgs.fetchzip {
    name = "Hammerspoon.app";
    url = "https://github.com/Hammerspoon/hammerspoon/releases/download/${version}/Hammerspoon-${version}.zip";
    sha256 = "12j9vylcxb7i3bn0v5x6zbxmnyyp7gh4am4vg48yv3hb54i73klx";
  };

  package = pkgs.runCommand "Hammerspoon-${version}" {} ''
    mkdir -pv $out/Applications/Hammerspoon.app
    cp -r ${release}/* $out/Applications/Hammerspoon.app
  '';

in {
  home.packages = [ package ];

  home.activation.hammerspoon = dagEntryAfter["linkgeneration"] (let
    linkName = "Hammerspoon.app";
    home = config.home.homeDirectory;
    applications = "${home}/.nix-profile/Applications";
    source = "${applications}/${linkName}";
    target = "${home}/Applications/";
  in ''
    rm -r ${target}/${linkName}
    osascript << EOF
      tell application "Finder"
      set mySource to POSIX file "${source}" as alias
      make new alias to mySource at POSIX file "${target}"
      set name of result to "${linkName}"
      end tell
    EOF
  '');
}

home-manager-path

ls -la /nix/store/jsczd16r60galp5acm6ilfg2pyjssf7z-home-manager-path/
total 24
dr-xr-xr-x     8 root  wheel     272 Dec 31  1969 .
drwxrwxr-t  2590 root  nixbld  88060 Oct 27 14:31 ..
lrwxr-xr-x     1 root  wheel      81 Dec 31  1969 Applications -> /nix/store/qgnj58776a3syzpjn99yiax67hfqa6lk-emacs-with-packages-25.3/Applications
dr-xr-xr-x    22 root  wheel     748 Dec 31  1969 bin
lrwxr-xr-x     1 root  wheel      57 Dec 31  1969 etc -> /nix/store/cjabqi6fm5qkq90ikznkqqxzg1fhahs6-zsh-5.4.2/etc
dr-xr-xr-x     5 root  wheel     170 Dec 31  1969 lib
lrwxr-xr-x     1 root  wheel      57 Dec 31  1969 sbin -> /nix/store/2inwapsm2c5yhxgd6cbqgwa7ipgbg77m-man-1.6g/sbin
dr-xr-xr-x    12 root  wheel     408 Dec 31  1969 share

tree

#> tree -L 2 /nix/store/qccgzdal0115i2p2snamzpmhginh9lpj-Hammerspoon-0.9.57/
/nix/store/qccgzdal0115i2p2snamzpmhginh9lpj-Hammerspoon-0.9.57/
└── Applications
    └── Hammerspoon.app