Shared via Rust Playground

playground.rs

fn main() {
    let g = vec![1, 5, 6, 9, 8];
    let r = 7;
    
    let mut i = g.iter().enumerate().peekable();
    while let Some((index, lhs_val)) = i.next() {
        let lookahead = i.peek();
        
        println!("{}, {} with lookahead {:?}", index, lhs_val, lookahead);
    }
    
    // resulting iteration would be
    // 0, 1 and includes 1, 5 & 2, 6
    // 3, 9
    // 4, 8
}