sumBy method

num sumBy(
  1. num selector(
    1. T
    )
)

Calculates the sum of all elements in the iterable by mapping them to numeric values.

Example:

var list = ['a', 'ab'];
var result = list.sumBy((s) => s.length); // 3

Implementation

num sumBy(num Function(T) selector) =>
    isEmpty ? 0 : map(selector).reduce((value, element) => value + element);