Especially useful for numeric types:

integerToNatural :: Integer -> Maybe Natural
integerToInt     :: Integer -> Maybe Int
intToWord        :: Int -> Maybe Word
wordToInt        :: Word -> Maybe Int

Maybe there could be some abstraction for such kind of things that can looks like this:

class PartialProjection small big where
    widen   :: small -> big
    shorten :: big -> Maybe small

Or even generalise this construction to be able to have Maybe or not have it in both directions.

Looks like Prism but dunno. To be discussed.