until -package:numeric-prelude -package:base-prelude -package:distribution-opensuse -package:Cabal -package:util -package:numhask -package:LambdaHack -package:conferer -package:free package:selective

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.