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Typeclasses

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class (Functor t, Foldable t) => Traversable t

Functors representing data structures that can be traversed from left to right. Methods:

• mapA : Applicative f => (a -> f b) -> t a -> f (t b) Map each element of a structure to an action, evaluate these actions from left to right, and collect the results.
• sequence : Applicative f => t (f a) -> f (t a) Evaluate each action in the structure from left to right, and collect the results.

Instances:

• instance Ord k => Traversable (Map k)
• instance Traversable TextMap
• instance Traversable Optional
• instance Traversable NonEmpty
• instance Traversable (Validation err)
• instance Traversable (Either a)
• instance Traversable []
• instance Traversable a

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Functions

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forA

forA : (Traversable t, Applicative f) => t a -> (a -> f b) -> f (t b) forA is mapA with its arguments flipped.