Mathieu Othacehe skribis: >> + (("--substitute" store-path destination) >> + ;; Download STORE-PATH and add store it as a Nar in file DESTINATION. > > add it to store? Oops. >> + const Strings args = { "substitute", "--query" }; >> + const std::map env = { { "_NIX_OPTIONS", settings.pack() } }; >> + std::unique_ptrfresh(new Agent(settings.guixProgram, args, env)); > > You should prefer make_unique to "new" calls. Apparently ‘make_unique’ is a C++14 thing and we don’t build against that standard (yet), so I left it as is. The next patch removes this use of ‘unique_ptr’ anyway.