Merge pull request #14 from haskell-works/newhoggy/new-whileNothingM-…

…function New `whileNothingM` function
haskell-works · Jan 5, 2025 · 3fa7333 · 3fa7333
2 parents 416e254 + ed41e02
commit 3fa7333
Showing 1 changed file with 6 additions and 0 deletions.
diff --git a/src/HaskellWorks/Control/Monad.hs b/src/HaskellWorks/Control/Monad.hs
@@ -2,6 +2,8 @@ module HaskellWorks.Control.Monad
   ( whileM,
     unlessM,
 
+    whileNothingM,
+
     repeatNUntilM_,
     repeatNWhileM_,
   ) where
@@ -18,6 +20,10 @@ unlessM act = do
   b <- act
   unless b $ unlessM act
 
+whileNothingM :: Monad m => m (Maybe a) -> m a
+whileNothingM act =
+  act >>= maybe (whileNothingM act) pure
+
 -- | Repeat an action n times until the action returns True.
 repeatNUntilM_ :: ()
   => Monad m