until -package:numeric-prelude -package:base-prelude -package:hosc -package:numhask -package:elerea -package:dunai package:selective -is:exact

untilRight :: (Monoid a, Selective f) => f (Either a b) -> f (a, b)
selective Control.Selective
Keep running an effectful computation until it returns a Right value, collecting the Left's using a supplied Monoid instance.