Map Functions are a feature.
Map is the name of a higher-order function that applies a given function to each element of a functor, e.g. a list, returning a list of results in the same order.
Languages with Map Functions include JavaScript, Haskell
[1,2.1].map(Math.round)
class Functor f where
fmap :: (a -> b) -> f a -> f b
(<$) :: a -> f b -> f a