hosc-0.21: Sound/Osc/Wait.hs

-- | Waiting (for replies).
module Sound.Osc.Wait where

-- * Wait

-- | Repeat action until predicate /f/ is 'True' when applied to result.
untilPredicate :: Monad m => (a -> Bool) -> m a -> m a
untilPredicate f act =
  let g p = if f p then recur else return p
      recur = act >>= g
  in recur

-- | Repeat action until /f/ does not give 'Nothing' when applied to result.
untilMaybe :: Monad m => (a -> Maybe b) -> m a -> m b
untilMaybe f act =
  let g p = maybe recur return (f p)
      recur = act >>= g
  in recur