Scala Programming Language Cheatsheet

Basic cheatsheet for Scala:

1. Variables and Data Types

// Immutable variable
val x: Int = 10

// Mutable variable
var y: String = "Hello"

// Data types
val a: Int = 5
val b: Double = 3.14
val c: Char = 'a'
val d: String = "Scala"

2. Control Structures

// If-else statement
val num = 10
if (num > 0) {
  println("Positive")
} else if (num < 0) {
  println("Negative")
} else {
  println("Zero")
}

// Match expression
val day = "Monday"
val result = day match {
  case "Monday" => "Start of the week"
  case "Friday" => "End of the week"
  case _ => "Other day"
}

3. Functions

// Defining a function
def add(x: Int, y: Int): Int = {
  x + y
}

// Anonymous function (lambda)
val multiply = (x: Int, y: Int) => x * y

// Higher-order function
def applyOperation(x: Int, y: Int, operation: (Int, Int) => Int): Int = {
  operation(x, y)
}

4. Collections

// List
val list = List(1, 2, 3, 4, 5)

// Map
val map = Map("a" -> 1, "b" -> 2, "c" -> 3)

// Set
val set = Set(1, 2, 3, 4, 5)

// For loop
for (i <- 1 to 5) {
  println(i)
}

// Functional operations on collections
val doubledList = list.map(_ * 2)
val filteredList = list.filter(_ % 2 == 0)

5. Classes and Objects

// Class definition
class Person(var name: String, var age: Int)

// Object (companion object)
object Person {
  def apply(name: String, age: Int): Person = new Person(name, age)
}

// Creating an instance
val person = new Person("Alice", 25)

// Accessing fields
println(person.name)

// Companion object usage
val person2 = Person("Bob", 30)

6. Traits and Mixins

// Trait definition
trait Speaker {
  def speak(): Unit
}

// Class with a trait
class Dog extends Speaker {
  def speak(): Unit = {
    println("Woof!")
  }
}

// Mixin
class Cat extends Speaker with Animal {
  def speak(): Unit = {
    println("Meow!")
  }
}

7. Pattern Matching

// Pattern matching in case classes
case class Person(name: String, age: Int)

val alice = Person("Alice", 25)

val result = alice match {
  case Person("Alice", 25) => "Matched Alice"
  case Person(name, age) => s"Matched $name with age $age"
  case _ => "No match"
}

8. Error Handling

// Option for optional values
val maybeValue: Option[Int] = Some(42)

// Handling Option
val result = maybeValue match {
  case Some(value) => s"Got the value: $value"
  case None => "No value"
}

// Try for exception handling
import scala.util.Try

val resultTry = Try {
  "123".toInt
}.getOrElse(0)

Remember to refer to the Scala documentation for more in-depth information and advanced features.

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