Tyson's blog

FunctionsWe have functions today:) Custom Sorting We can sort any type with any comparatror But what if we want to sort points by their distance from a reference point In general: what if the comparator needs more parameters than just the two elements? We can dynamically create a new function with the additional parameters “built-in” Returning Functions We can write a function / method that takes all the needed parameters and returns a funcrtion that fits the signature of a comparator Th ...

Recursion123456789101112def computeGeometricSum(n: Int): Int = { if(n <= 0){ 0 }else{ n + computeGeometricSum(n-1) }}def main(args: Array[String]): Unit = { val resullt: Int = computeGeometricSum(3) println(result)} Computes the geometric sum of the input Ex: if n == 3, geometric sum is 3+2+1 == 6 Base Case: An input with a trivial output Geometric sum of 0 is defined as 0 We could also add 1 -> 1 a ...

Merge Sort / RecursionTaco Tuesday!!! Runtime Analysis Last time we said Selection sort is inefficient Let’s be more specific We’ll measure the asymptotic runtime of the algorithm Often use big-O notation Count the number of “steps” the algorithm take A step is typically a basic operation (+, -, &&, etc) Asymptotic runtime Measures the order of magnitude of the runtime in relation to the size of the input Name the input size n For sorting - Size of the input is the number of ...

Sorting - RevisitedWith First-Order Functions SortingOrder elements in a data structure according to a comparator function 123val numbers = List(5, -23, -8, 7, -4, 10)val numberSorted = numbers.sortedprintln(numberSorted) // List(-23, -8, -4, 5, 7, 10) The sorted method returns a new List containing the same elements as the original, but in sorted order Integer values have a default comparator Less than function If an element is less than another element, it must be placed before the other e ...

State Pattern - Demo!Go check the video, no content on this page!!! State Pattern - Closing ThoughtsState pattern trade-offs Pros Oranizes code when a single class can have very different behavior in different circumstances Each implemented method is only concerned with the reaction to 1 event (API call) in 1 state Easy to change or add new behavior after the state pattern is setup Cons Can add complexity if there are only a few states or if behavior does not change significantly across state ...

State Pattern - More ExampleCheck the example Jumper below:) Jumper 2 Player vertical scrolling platform Screen scrolls up as the players climb the platforms The bottom of the screen is game over Goal: Climb faster than the other player We’ve seen how physics was added to the game Platforms / Wall extend StaticObject Players extend DynamicObject FUlly compatible with the Physics Engine HW Jumper - PhysicsWalls and Platforms extend StaticObject Add behavior after collision w ...

State Pattern Design Patterns Approaches to common programming design problems There are many design patterns We’ll only focus on the state pattern in this course For more patterns, search “The Gang of Four” The Primary goal of design patterns is to simplify the Design and Maintainability of our programs Applies Polymorphism Every object contains state and behavior We use state variables to change the state of an object and its behavior can depend on this state What if we wa ...

JSONAn Application of Polymorphism JSON - Reminder JSON is [mostly] used to communicate betweent programming languages Consist of 6 types String Number Boolean Array Object Null In Python json.dumps to convert from Python types to JSON string json.loads to convert from JSON string to Python types In JavaScript JSON.stringify to convert from JavaScript types to JSON string JSON.parse to convert from JSON string to JavaScript types JSON What about Scala?{“timestamp”:1550774961,”message” ...

Polymorphism Scala Type Hierarchy-1 All objects share Any as their base typoes Classes extending AnyVal will be stored on the stack *Unless they are a state variable of an object Classes extending AnyRef will be stored on the heap Recall Scala Type Hierarchy-2 Classes you define extend AnyRef by default HealthPotion has 6 different types123456val potion1: HealthPotion = new HealthPotion(new PhysicsVector(), new PhysicsVector(), new PhysicsVector(), 6) val potion2: InanimateObject = new Heal ...

Inheritance Scala Type Hierarchy All objects share Any as their base types Classes extending AnyVal will be stored on the stack Classes extending AnyRef will be stored on the heap Overview Let’s do some world building If we’re making a game, we’ll want various objects that will interact with each other we’ll setup a simple game where Each player has a set health and strength Players can pick up and throw balls If a player gets hit with a ball, they lose health Players can collect health pot ...