Rust: The Ultimate Beginner's Guide to Learn Rust programming Step by Step by Bach John

Author:Bach, John [Bach, John]
Language: eng
Format: epub
Published: 2020-08-22T16:00:00+00:00

0

0

one

one

0

one

two

3

0

3

3

6

We have called fold () with these arguments:

# (1..4)

.fold (0, | sum, x | sum + x);

So 0 is our base, sum is our accumulator, and x is our element. In the first iteration, we assign sum to 0 and x is the first element in our range, 1 . Then we add sum and x , which gives us 0 + 1 = 1 . In the second iteration, that value becomes the value of our accumulator, sum , and the element is the second element in the range, 2 . 1 + 2 = 3 and likewise becomes the accumulator value for the last iteration. In that iteration, x is the last element, 3 , and 3 + 3 = 6 , the final result for our sum . 1 + 2 + 3 = 6 , that's the result we get.

Whew. Fold may be a little strange at first glance, but once it clicks, you can use it everywhere. Whenever you have a list of things, and need a single result, fold is appropriate.

Consumers are important because of an additional property of iterators that we haven't talked about yet: laziness. Let's talk more about iterators and you'll see why consumers are important.

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