dhiguero/scala-exercises

Scala exercises

scala-exercises

Introduction

The purpose of this repository is to provide an skeleton to solve a series of scala exercises.

Exercises

Exercise 1

Provide a generic method to process a list of any type and apply a function to the elements of the list.

Example 1: Transform each element into an arbitrary string representation.

val l = List(1,2,3,4,5)
val r1 = processList(l, transformToString)
println(r1)

Output:

 Map(5 -> string: 5, 1 -> string: 1, 2 -> string: 2,
      3 -> string: 3, 4 -> string: 4) 

Example 2: Transform each number obtain its square value.

val r2 = processList(l, square)
println(r2)`

Output:

Map(5 -> 25, 1 -> 1, 2 -> 4, 3 -> 9, 4 -> 16)

Notes

• Provide two implementations. One of them must use foldLeft.
• The elements of the list can be of any type A.

Exercise 2

Define a Person case class that contains the following attributes:

• name
• age
• mail

Code a method to obtain a map of users indexed by age.

def groupByAge(persons: List[Person]): Map[Int, List[Person]]

Notes

• Provide two implementations. One of them must use foldLeft.
• Generate a list of 50 persons using random names, mails, and ages.

Exercise 3

1. Define a superclass called Vehicle.
2. Define two traits: AirVehicle, and GroundVehicle.
3. Define a class Car, Bus, Helicopter and Plane that extend both Vehicle and the previous traits.
4. Each vehicle is identified by a name.
5. An air vehicle has the following attributes: airspeed, and maxSpeed.
6. A ground vehicle has a maxSpeed.

Provide a method to filter ground vehicles.

def filterGroundVehicles(vehicles: List[Vehicle]): List[GroundVehicle]

Provide a method to obtain the average maximum speed.

def getAverageMaxSpeed(vehicles: List[Vehicle]): Double

Notes

• Use pattern matching in the filter function.
• Generate a list of 50 vehicles using random values.

Extensions

• Generate a new vehicle that is both AirVehicle and GroundVehicle.

Exercise 4

Define a linked list data structure with the following public methods:

• head: Obtain the first element of the list.
• last: Obtain the last element of the list.
• isEmpty: Whether the list is empty.
• get(index): Get the element at possition index if possible. Return an option.
• add: Add a new element to the list.
• size: Get the size of the list.

Notes

• The list must accept generic types.
• The list is mutable but it is implemented using in-mutable structures.
• The list must be implemented as a linked list.
• Use of scala or Java collections as internal structures is forbidden.