map
1. <mathematics> function.
2. <programming> In functional programming, the most common higher-order function over lists. Map applies its first argument to each element of its second argument (a list) and returns the list of results.
map :: (a -> b) -> [a] -> [b] map f [] = [] map f (x:xs) = f x : map f xs
This can be generalised to types other than lists.