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object EvalExample2 extends App {
    
    def twice(value: Int): Int = value * value
    
    def divideBy2(value: Int): Int = value / 2
    
    val value = 42
    val intermediateResult = twice(value)
    val result = divideBy2(intermediateResult)
    println(result)

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object EvalExample1 extends App {
    
    val eager = Eval.now {
        println("Hey !! I am eager eval")
        "Hello Eval Eager"
    }
    
    val lazyEval = Eval.later {
        println("Hey !! I am lazy eval")
        "Hello Eval Lazy"

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object IdExample1 extends App {

  def sumSquare[F[_]: Monad](a: F[Int], b: F[Int]): F[Int] = {
    a.flatMap(x => b.map(y => x*x + y*y))
  }

  import cats.instances.list._
  import cats.instances.option._

  val result1 = sumSquare(Option(2), Option(5))

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import cats.Functor
import cats.instances.list._

 val ints = List(1, 2, 3, 4, 5)
 Functor[List].map(ints)(_.toString)

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trait Functor[F[_]] {
  def map[A, B](fa: F[A])(f: A => B): F[B]
}

val listFunctor = new Functor[List] {
  override def map[A, B](fa: List[A])(f: A => B): List[B] = fa match {
    case Nil => Nil
    case h :: t => f(h) :: map(t)(f)
  }
}

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object Example1Monoid extends App {

  case class TwitterUser(username: String, followers: Int) extends Ordered[TwitterUser] {
    override def compare(that: TwitterUser): Int = {
      val c = this.followers - that.followers
      if(c == 0) this.username.compareTo(that.username) else c
    }
  }

  implicit val twitterUserMonoid = new Monoid[TwitterUser] {

harmeetsingh0013

import cats.kernel.Monoid

object Example1Monoid extends App with Data {

  implicit val moneyMonoid = new Monoid[Money] {
    override def empty: Money = Money(0, 0)

    override def combine(x: Money, y: Money): Money = {
      Money(x.dollars + y.dollars + ((x.cents + y.cents) / 100),
        (x.cents + y.cents) % 100)

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object Example4Semigroup extends App with Data {

  implicit val moneySemigroup = new Semigroup[Money] {
    override def combine(x: Money, y: Money): Money = {
      Money(x.dollars + y.dollars + ((x.cents + y.cents) / 100),
        (x.cents + y.cents) % 100)
    }
  }

  import cats.instances.int._

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object Example1Semigroup extends App with Data {

  trait Addable[T] {
    def add(a: T, b: T): T
  }

  implicit val addInt = new Addable[Int] {
    override def add(a: Int, b: Int): Int = a + b
  }

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// add implementation for int type
implicit val addInt = new Addable[Int] {
  override def add(a: Int, b: Int): Int = a + b
}

// add implementation for money type
implicit val addMoney = new Addable[Money] {
  override def add(a: Money, b: Money): Money = {
    Money(a.dollars + b.dollars + ((a.cents + b.cents) / 100),
      (a.cents + b.cents) % 100)