[Haskell-cafe] Feeding a monad into itself

Jake jake.waksbaum at gmail.com
Thu Jul 20 17:26:17 UTC 2017


I have a function f :: a -> Maybe a that I want to feed into itself with
some initial input until it returns Nothing.

untilNothing :: (a -> Maybe a) -> a -> a
untilNothing f x = case f x of
                            Just x' -> untilNothing f x'
                            Nothing -> x

Is there a better way to do this? I feel like there is something more
general going on with Monads being fed into themselves, but maybe I'm
wrong. Thoughts?
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