Try It Yourself - SyntaxStudy Editor

HTML / CSS / JS

use std::collections::HashMap;

fn main() {
    let words = vec!["apple", "banana", "cherry", "apricot", "blueberry", "avocado"];

// Chain of adapters — no intermediate allocations
    let a_words_upper: Vec<String> = words.iter()
        .filter(|w| w.starts_with('a'))
        .map(|w| w.to_uppercase())
        .collect();
    println!("a-words: {:?}", a_words_upper);

// fold — general reduction
    let total_len: usize = words.iter().fold(0, |acc, w| acc + w.len());
    println!("total char count: {total_len}");

// flat_map — flatten nested iterables
    let letters: Vec<char> = words.iter()
        .flat_map(|w| w.chars())
        .filter(|c| *c == 'a')
        .collect();
    println!("count of 'a': {}", letters.len());

// enumerate + collect into HashMap
    let index_map: HashMap<usize, &str> = words.iter()
        .enumerate()
        .map(|(i, &w)| (i, w))
        .collect();
    println!("word at index 2: {}", index_map[&2]);

// zip two iterators
    let nums = vec![1u32, 2, 3];
    let labels = vec!["one", "two", "three"];
    let zipped: Vec<_> = nums.iter().zip(labels.iter()).collect();
    println!("zipped: {:?}", zipped);

// scan — accumulating state mid-stream
    let running: Vec<u32> = (1..=5)
        .scan(0u32, |state, x| { *state += x; Some(*state) })
        .collect();
    println!("running sums: {:?}", running);

// any / all
    println!("any > 5 chars: {}", words.iter().any(|w| w.len() > 5));
    println!("all non-empty: {}", words.iter().all(|w| !w.is_empty()));
}