Description
The following commit added significant complexity to the exercise: 8e1f617
I understand the desire to show people functional programming, I love it as much as the next Rust developer. But this exercise comes pretty much right after primitive types.
Even using vectors is a stretch here, the book itself covers vectors only much later. But I think that's withing reason here, because vectors are necessary to do almost anything and most programmers will be familiar with something similar. So I think it's justified to cover vectors a bit earlier than the book.
However... iterators? map? collect? lambda syntax? I find this completely unjustified. If this content is not covered in the dedicated section for iterators, it can be moved there.
Please consider removing the vec_map part from that exercise so as not to overwhelm new learners too early.