Combinators

Alternation

alternate :: (Foldable f, Alternative g) => f a -> g a

Generalization over many common natural transformations, including:

• listToMaybe
• maybeToList
• toList

• either (const Nothing) Just

alternateMap :: (Foldable f, Alternative g) => (a -> b) -> f a -> g b

alternate extended with ability to map the wrapped value.

alternateMapM :: (Foldable f, Alternative g) => (a -> g b) -> f a -> g b

alternateMap extended with ability to do the mapping in the Alternative context.

Folding

intercalate :: (Foldable f, Monoid a) => a -> f a -> a

A generic version of the original list-specialized version:

intercalate :: [a] -> [[a]] -> [a]

intercalateMap :: (Foldable f, Monoid m) => m -> (a -> m) -> f a -> m

intercalate extended with ability to map the wrapped value.

Traversal

iforM :: (Traversable f, Monad m) => f a -> (Int -> a -> m b) -> m (f b)

Indexed version of forM.

itraverse :: (Traversable f, Monad m) => (Int -> a -> m b) -> f a -> m (f b)

Indexed version of traverse.