Generics on Rust - StudentRecord Non-Generic

student_record_u8.rs

use std::collections::HashMap;

pub struct StudentRecord {
    student_id: u32,
    marks: Vec<u8>,
}

impl StudentRecord {
    pub fn new(student_id: u32) -> Self {
        Self {
            student_id,
            marks: Vec::new(),
        }
    }

    pub fn add_mark(&mut self, mark: u8) {
        self.marks.push(mark);
    }

    pub fn avg(&self) -> u8 {
        let mut sum = 0;
        for mark in &self.marks {
            sum += mark;
        }
        sum.checked_div(self.marks.len() as u8).expect("No marks")
    }

    pub fn mode(&self) -> u8 {
        let mut map = HashMap::new();
        for mark in &self.marks {
            *map.entry(mark).or_insert(0) += 1;
        }
        *map
            .into_iter()
            .max_by_key(|&(_, count)| count)
            .map(|(mark, _)| mark)
            .expect("No marks")
    }

    pub fn median(&mut self) -> u8 {
        self.marks.sort();
        *self.marks.get(self.marks.len() / 2).expect("No marks")
    }
}