Functor class is used for types that can be mapped over.
: Functor f => f a -> b -> f b
Replace all locations in the input (on the left) with the given value (on the right).
: Functor f => f a -> (a -> b) -> f b
Map a function over a functor. Given a value
asand a function
as <&> fis
f <$> as. That is,
<$>but the arguments are in reverse order.