úÎ ê Ñ     (c) Fumiaki Kinoshita 2015BSD3'Fumiaki Kinoshita <fumiexcel@gmail.com> experimental non-portableNoneLike traverse7, but you can remove elements instead of updating them. traverse f "a  (  . f)A definition of ! must satisfy the following laws: identity ( . Just) "a  compositionCompose . fmap ( f) .  g "a  (Compose . fmap ( f) . g))Parametricity implies the naturality law: t .  f =  (t . f)Minimal complete definition:  or ;. The default definitions can be overriden for efficiency. is  with its arguments flipped.         witherable-0.1.2.1Data.Witherable WitherablewithermapMaybe catMaybesfilterAfilterwitherMblightM$fWitherableSeq$fWitherableVector$fWitherableConst$fWitherableProxy$fWitherableHashMap$fWitherableMap$fWitherableIntMap$fWitherable[]$fWitherableEither$fWitherableMaybebaseGHC.Basefmap Data.MaybeJustControl.Applicativepure