Iterators in Rust
From the Rust cheat sheet · Collections & Iterators · verified Jul 2026
Iterators
Transform collections with iterator adaptors and consumers.
rust
let nums = vec![1, 2, 3, 4, 5];
// Map, filter, collect
let doubled: Vec<i32> = nums.iter().map(|x| x * 2).collect();
let evens: Vec<&i32> = nums.iter().filter(|x| *x % 2 == 0).collect();
// Chaining
let result: i32 = nums.iter()
.filter(|x| *x % 2 != 0)
.map(|x| x * x)
.sum();💡 Iterators are lazy — .map() and .filter() do nothing until you .collect() or .sum()
⚡ .iter() borrows, .into_iter() consumes, .iter_mut() mutably borrows the collection
📌 Use turbofish ::<Vec<_>> with .collect() when the compiler can't infer the target type
🟢 Chain adaptors freely — Rust optimizes iterator chains to be as fast as hand-written loops
iteratorsmapfiltercollect