Control.Safely

safely :: forall m a. MonadRec m => (forall safe. MonadRec safe => (m ~> safe) -> (safe ~> m) -> safe a) -> m a

Make a control operator stack-safe.

For any MonadRec, we can form the Monad FreeT Identity m in which arbitrarily-associated binds are stack-safe.

This function performs the wrapping and unwrapping for us, and provides a pair of natural transformations to lift and lower actions to and from the safe monad.

This means that we can write stack-safe monadic code for any MonadRec by simply writing the naive implementation, and wrapping it in a call to safely:

traverseSafely :: forall m a. MonadRec m => (a -> m Unit) -> List a -> m Unit
traverseSafely f xs = safely \lift lower ->
  let
    go Nil = pure unit
    go (Cons x xs) = do
      lift (f x)
      go xs
  in go xs

replicateM_ :: forall m a. MonadRec m => Int -> m a -> m Unit

Safely replicate an action N times.

traverse_ :: forall f m a. Foldable f => MonadRec m => (a -> m Unit) -> f a -> m Unit

Safely traverse a foldable container.

for_ :: forall f m a. Foldable f => MonadRec m => f a -> (a -> m Unit) -> m Unit

Safely traverse a foldable container.

foldM :: forall m a b. MonadRec m => (a -> b -> m a) -> a -> List b -> m a

Perform a monadic fold, safely.