let
  sources = import ./Sources.nix { sourcesFile = ./Sources.json; };

  config = {
    allowAliases = true;
    allowBroken = true;
    allowUnfree = true;
    checkMeta = true;
    cudaSupport = true;
  };

  system = __currentSystem;

  # override pinned deps with our sources, this must come before other
  # package overlays, because of the 'null' from 'overrideSource'
  depsOverlay = _: pkgs: pkgs.overridePinnedDeps pkgs.overrideSource;

  overlays = [
    (_: _: { inherit sources; })
    (import ./CcacheWrapper.nix)
    (import ./Functions.nix)
    depsOverlay
    (import ./Deps.nix)
    (import ./Python.nix)
    (import ./Haskell.nix)
  ];

  nixos-unstable-small =
    import sources.nixos-unstable-small { inherit system config overlays; };

in {
  nixos-24_05 = import sources.nixos-24_05 {
    inherit system config;
    overlays = overlays ++ [
      (_: _: {
        # backport newer packages from unstable
        unstable = nixos-unstable-small.pkgs;
      })
    ];
  };

  inherit nixos-unstable-small;
}