Hi Ivan empty is fine as is, obviously with a Monoid instance as well, people can choose to use mempty which removes potential name clashes. I was thinking of (<$>) and (<+>), though I was forgetting that (<+>) is actually ArrowPlus. If you are mostly gifting angles as notation to Applicative, maybe a pretty print library can live with fewer infix ops? Though you could still define fixities for the binary cases: infixr 6 `sep1` Or maybe steal the notation form Vector-Space (^+^) as cases where you would want both imported at the same time may be uncommon. Although "trivial" proposals often get rejected for changes to Base, I suspect a proposal for (<>) as a synonym for `mappend` might have legs, it would certainly have a lot of support...