Generic Types, Traits, and Lifetimes

Every programming language has tools for effectively handling duplication of concepts. In Mana, one such tool is generics: abstract stand-ins for concrete types or other properties.

This chapter covers:

• Generic Data Types — Write functions and types that work with any type
• Traits: Defining Shared Behavior — Define behavior that types can implement
• Validating References with Lifetimes — Ensure references are valid

Removing Duplication

Consider finding the largest number:

fn largest_int(list: Vec<int>) -> int {
    let mut largest = list[0]
    for item in list {
        if item > largest {
            largest = item
        }
    }
    return largest
}
 
fn largest_char(list: Vec<char>) -> char {
    let mut largest = list[0]
    for item in list {
        if item > largest {
            largest = item
        }
    }
    return largest
}

These functions are identical except for the type. Generics eliminate this duplication.

Let's start with Generic Data Types.