The example can be written like this though:

  let codes: Vec<HuffmanCode> = data_table.iter()
            .zip(&code_lengths)
            .zip(&code_table)
            .map(|((&value, &length), &code)| {
                HuffmanCode {
                    length: length,
                    code: code,
                    value: value,
                }
            })
            .collect();