[Haskell-cafe] [announcement] filtrable: class of filtrable containers

I quietly posted this library to Hackage nearly a year ago, but lately learned that some seeking such a package had difficulty finding it, so i announce it now ☺ https://hackage.haskell.org/package/filtrable class Functor f => Filtrable f where mapMaybe :: (a -> Maybe b) -> f a -> f b catMaybes :: f (Maybe a) -> f a filter :: (a -> Bool) -> f a -> f a For laws, see docs on Hackage.