Data.FunctorWithIndex

class (Functor f) <= FunctorWithIndex i f | f -> i where

A Functor with an additional index. Instances must satisfy a modified form of the Functor laws

mapWithIndex (\_ a -> a) = identity
mapWithIndex f . mapWithIndex g = mapWithIndex (\i -> f i <<< g i)

and be compatible with the Functor instance

map f = mapWithIndex (const f)

Members

• mapWithIndex :: forall b a. (i -> a -> b) -> f a -> f b

Instances

• FunctorWithIndex Int Array
• FunctorWithIndex Unit Maybe
• FunctorWithIndex Unit First
• FunctorWithIndex Unit Last
• FunctorWithIndex Unit Additive
• FunctorWithIndex Unit Dual
• FunctorWithIndex Unit Conj
• FunctorWithIndex Unit Disj
• FunctorWithIndex Unit Multiplicative

mapDefault :: forall b a f i. FunctorWithIndex i f => (a -> b) -> f a -> f b

A default implementation of Functor's map in terms of mapWithIndex