{ stdenv, writeScript, runCommand, nix, bash, git, jq, nix-prefetch-scripts, coreutils, common-updater-scripts, gnugrep, gnused, curl }:
{ repoName, attrPath ? repoName, versionPolicy ? "release" }:
let
  script = ./update.sh;

  updateScript = runCommand "update.sh" {
    inherit bash git jq nix coreutils gnugrep gnused curl;
    # These weren't being substituted
    nix_prefetch_scripts = nix-prefetch-scripts;
    common_updater_scripts = common-updater-scripts;
  } ''
    substituteAll ${script} $out
    chmod +x $out
  '';

  versionFlag = { "release" = "-r"; "master" = "-m"; }.${versionPolicy};

in [ updateScript versionFlag repoName attrPath ]