On 14-09-2022 19:18, Lukasz Olszewski wrote: > Additionally this fails even when used like this: > > (define inferior > (mlambda () > (inferior-for-channels channels))) This makes it lazy (not eager). > (lookup-inferior-packages (inferior) "somepackage") You are running (inferior) directly after defining the lazy thing, making it effectively _eager_ (not lazy) again. Instead of doing this on the top-level, move the lookup-inferior-packages to inside the 'inputs' or 'native-inputs', to _keep_ it lazy. Greetings, Maxime.