Practice Time: Lambdas

 

Practice Time

In this practice, you are going to write the the first part of a higher-order functions game. You will implement everything, except the higher-order functions. Let’s get started.

1. Create a new file.
2. Create an enum class, Directions, that has the directions NORTH, SOUTH, EAST and WEST, as well as START, and END.
3. Create a class Game.
4. Inside Game, declare a var, path, that is a mutable list of Direction. Initialize it with one element, START.
5. Create 4 lambdas, north, south, east, and west, that add the respective direction to the path.
6. Add another lambda, end, that:
   • Adds END to path
   • Prints “Game Over”
   • Prints the path
   • Clears the path
   • Returns false
7. Create a main function.
8. Inside main(), create an instance of Game.
9. To test your code so far, in main() print the path, then invoke north, east, south, west, and end. Finally, print the path again.

You should see this output:

> [START]
Game Over: [START, NORTH, SOUTH, EAST, WEST, END]
[]

// File:            Main.kt
// Programmer:      Engineer Nolverto Urias Obeso
// Creation Date:   06/24/2023
// Email:           nolvertou@gmail.com
// Description:     Practice Time of lambdas

// TODO 1: Create a new file
// TODO 2: Create an enum class, Directions, that has the directions NORTH, SOUTH, EAST and WEST,
//  as well as START, and END.
enum class Direction{NORTH, SOUTH, EAST, WEST, START, END}

// TODO 3: Create a class Game.
class Game(){
    var path: MutableList<Direction> = mutableListOf(Direction.START)

    // TODO 5: Create 4 lambdas, north, south, east, and west,
    //  that add the respective direction to the path.
    val addNorth = {path.add(Direction.NORTH)}
    val addSouth = {path.add(Direction.SOUTH)}
    val addEast = {path.add(Direction.EAST)}
    val addWest = {path.add(Direction.WEST)}

    // TODO 6: Add another lambda, end, that:
    //  Adds END to path
    //  Prints “Game Over”
    //  Prints the path
    //  Clears the path
    //  Returns false
    val end:() -> (Boolean) = { ->
        path.add(Direction.END)                           // Adds END to path
        println("Game Over")                              // Prints “Game Over”
        println("path: $path")                            // Prints the path
        for(item in path.indices) path.removeAt(0)  // Clears the path
        println("path is cleaned: $path")                 // Prints the path after clean it
        false                                             // Returns false
    }
}

// TODO 7: Create a main function.
fun main() {

    // TODO 8: Inside main(), create an instance of Game.
    val game = Game()

    // TODO 9: To test your code so far, in main() print the path, then invoke
    //  north, east, south, west, and end. Finally, print the path again.
    println(game.path)
    game.addNorth()
    game.addEast()
    game.addSouth()
    game.addWest()
    println(game.end()) // It verifies if the return is false
}

Output: 

[START]
Game Over
path: [START, NORTH, EAST, SOUTH, WEST, END]
path is cleaned: []
false