Maps and filters are typical for functional languages. A map is a function of the formmap(func, coll), where func is a (often anonymous) function that is successively applied to every element of the coll collection, so map returns a new collection. Some examples are as follows:
map(x -> x * 10, [1, 2, 3])returns[10, 20, 30]cubes = map(x-> Base.power_by_squaring(x, 3), collect(1:5))returns[1, 8, 27, 64, 125]
Note
power_by_squaring is an internal function in Base, which means it is not exported, so it has to be qualified with Base.
The map function can also be used with functions that take more than one argument. In this case, it requires a collection for each argument; for example, map(*, [1, 2, 3], [4, 5, 6]) works per element and returns [4, 10, 18].
When the function passed to map requires several lines, it can be a bit unwieldy to write as an anonymous function. For instance, consider using the following function:
map( x-> begin
...