Example
Iterator methods can be broken into two distinct groups:
Adapters
Adapters take an iterator and return another iterator
// Iterator Adapter
// | |
let my_map = (1..6).map(|x| x * x);
println!("{:?}", my_map);
Map { iter: 1..6 }
Note that the values were not enumerated, which indicates that iterators are not eagerly evaluated — iterators are "lazy".
Consumers
Consumers take an iterator and return something other than an iterator, consuming the iterator in the process.
// Iterator Adapter Consumer
// | | |
let my_squares: Vec<_> = (1..6).map(|x| x * x).collect();
println!("{:?}", my_squares);
[1, 4, 9, 16, 25]
Other examples of consumers include find, fold, and sum.
let my_squared_sum: u32 = (1..6).map(|x| x * x).sum();
println!("{:?}", my_squared_sum);
55
