Function nums_sum1

publication/code/chapter05/nums_sum12.rs:3–10

(nums: &[i32])

// nums_sum12.rs

fn nums_sum1(nums: &[i32]) -> i32 {
    if 1 == nums.len() {
        nums[0]
    } else {
        let first = nums[0];
        first + nums_sum1(&nums[1..])
    }
}

fn nums_sum2(nums: &[i32]) -> i32 {
    if 1 == nums.len() {