Rust: What is the difference between filter and take_while?

filter — keep matching items. take_while — take until condition fails.

filter:

• Check each item.
• Keep all matching.
• Non-destructive.

take_while:

• Take while true.
• Stop on first false.
• Destructive.

1let v = vec![1, 2, 3, 4, 5];
2
3// Filter: keep evens
4let evens: Vec<&i32> = v.iter().filter(|&&x| x % 2 == 0).collect();
5// [2, 4]
6
7// Take while less than 4
8let taken: Vec<&i32> = v.iter().take_while(|&&x| x < 4).collect();
9// [1, 2, 3]

Key: filter for conditional selection, take_while for prefix.