Traversable package:hedgehog

Functors representing data structures that can be transformed to structures of the same shape by performing an Applicative (or, therefore, Monad) action on each element from left to right. A more detailed description of what same shape means, the various methods, how traversals are constructed, and example advanced use-cases can be found in the Overview section of Data.Traversable#overview. For the class laws see the Laws section of Data.Traversable#laws.

Barbie-types that can be traversed from left to right. Instances should satisfy the following laws:

t . btraverse f   = btraverse (t . f)  -- naturality
btraverse Identity = Identity           -- identity
btraverse (Compose . fmap g . f) = Compose . fmap (btraverse g) . btraverse f -- composition

There is a default btraverse implementation for Generic types, so instances can derived automatically.

Deprecated: Replace with Hedgehog.TraversableB (defined in Data.Functor.Barbie) which can be derived automatically using GHC.Generics