nix-output-monitor: comment and cleanup

{

  haskell,

  expect,

  haskellPackages,

  installShellFiles,

  lib

  lib,

}: let

  inherit (haskell.lib.compose) justStaticExecutables overrideCabal;

  overrides = {

    passthru.updateScript = ./update.sh;

    # nom has unit-tests and golden-tests

    # golden-tests call nix and thus can’t be run in a nix build.

    testTarget = "unit-tests";

    buildTools = [installShellFiles];

    postInstall = ''

      ln -s nom "$out/bin/nom-build"