Welcome back! You've previously learned about the basics of Clojure and how to work with simple data types. Now, let's move forward and explore another important aspect of programming with Clojure: numbers. Understanding different types of numbers and how to manipulate them is key to managing various elements in our Clojure shooter game.

In this lesson, we will dive into the various types of numbers available in Clojure and how they interact with each other. Specifically, we will cover:

• Different types of numbers such as Integers, Big Integers, Ratios, Big Decimals, and Floating Points.
• How to mix and operate with different numeric types.
• Handling arithmetic overflow and utilizing Clojure's auto-promotion capabilities to manage large numbers.

By the end of this lesson, you'll be comfortable handling numeric operations in Clojure, a skill that will allow you to manage game statistics, perform complex calculations, and much more.

Here's a quick look at some code you’ll be able to understand and write:

Clojure
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1;; Different types of numbers
2(def player-health 100) ;; Integer (Contagiousness 0 - Lowest)
3(def max-health 100N) ;; Big Integer (Contagiousness 1)
4(def damage-ratio 10/2) ;; Ratio (Contagiousness 2)
5(def weapon-accuracy 0.8M) ;; Big Decimal (Contagiousness 3)
6(def enemy-distance 20.5) ;; Floating Point (Contagiousness 4 - Highest)
7
8;; Mixing numbers of different types
9(def mixed-sum-1 (+ player-health max-health)) ;; Big Integer
10(def mixed-sum-2 (+ player-health max-health damage-ratio)) ;; Ratio
11(def mixed-sum-3 (+ player-health max-health damage-ratio weapon-accuracy)) ;; Big Decimal
12(def mixed-sum-4 (+ player-health max-health damage-ratio weapon-accuracy enemy-distance)) ;; Floating Point
13
14;; Overflow and auto-promoting to big integer
15;; (def score-overflow (* 4037000499 3037000500)) ;; ArithmeticException integer overflow
16
17(def auto-promoted-score (*' 4037000499 3037000500)) ;; Big Integer

Below is a table summarizing different numeric types in Clojure:

Contagiousness in this context refers to how operations involving mixed numeric types in Clojure will result in a type promotion to the "higher" type. For example, if you add an Integer and a Big Decimal, the result will be a Big Decimal because Big Decimal is more "contagious" (higher up in the hierarchy) than an Integer. The numerical types with higher contagiousness will impose their type on the result.

Numbers are fundamental to almost all programming tasks. In our game, keeping track of the hero's health, calculating damage, measuring distances, and maintaining accuracy all rely on correctly managing numbers. Whether you're adding score points, calculating damage, or working with large data values, understanding how to handle different types of numbers and avoid pitfalls like arithmetic overflow is crucial.

Mastering these concepts ensures that your program runs efficiently and accurately, enhancing both your game development and overall programming skills. Let's dive into the practice section and explore these numeric types and operations in depth!