More natural takeWhile analogue?

We have

takeWhile :: Dupable a => (a %1 -> Bool) -> [a] %1 -> [a]
takeWhile _ [] = []
takeWhile p (x : xs) =
  dup2 x & \(x', x'') ->
    if p x'
      then x'' : takeWhile p xs
      else (x'', xs) `lseq` []

Should we add a version that (a bit like mapMaybe for filter) relaxes the constraint while adding flexibility?

mapWhileJust :: Consumable a => (a %1 -> Maybe b) -> [a] %1 -> [b]
mapWhileJust _ [] = []
mapWhileJust p (x : xs) =
  case p x of
    Nothing -> xs `lseq` []
    Just x' -> x' : mapWhileJust p xs

Unfortunately, I don't see any similarly intuitive analogue of dropWhile.

Start by reading the existing takeWhile implementation and related mapMaybe API, then compare them with the proposed mapWhileJust signature and semantics. The issue needs an agreed API, including whether a dropWhile analogue is required, before implementation can begin; done means the design is resolved and covered by appropriate tests.