We definitely should /not/ repeat the choice made for
Data.List.NonEmpty.NonEmpty. Using non-empty lists /always/ requires a
type synonym, like
import qualified Data.List.NonEmpty as NEList
type NEList = NEList.NonEmpty
which is quite ugly, and type synonyms are sometimes expanded in GHC
error messages, which causes additional trouble.
I’m not sure what you mean here by “always requires a type synonym”—I typically use NonEmpty like any other module meant to be imported qualified, like Text, Vector, Map, Set, &c.:
import Data.List.NonEmpty (NonEmpty)
import qualified Data.List.NonEmpty as NonEmpty -- or NE if I’m lazy
example :: NonEmpty X -> Y