dart:collection

map method

Iterable<T> map<T>(T f(E element))

Returns a new lazy Iterable with elements that are created by calling f on each element of this Iterable in iteration order.

This method returns a view of the mapped elements. As long as the returned Iterable is not iterated over, the supplied function f will not be invoked. The transformed elements will not be cached. Iterating multiple times over the returned Iterable will invoke the supplied function f multiple times on the same element.

Methods on the returned iterable are allowed to omit calling f on any element where the result isn't needed. For example, elementAt may call f only once.

Source

Iterable<T> map<T>(T f(E element)) =>
    new EfficientLengthMappedIterable<E, T>(this, f);