rajeevprasanna’s gists

rajeevprasanna / statefactorial.scala

Created June 29, 2017 10:35 — forked from calvinlfer/statefactorial.scala

Factorial using the State monad

	import cats.data.State
	import cats.data.State._

	def factorialWithState(x: Int): Int = {
	def stateFactorial: State[Int, Int] =
	get.flatMap(x =>
	if (x <= 1)
	State.pure(1)
	else {
	set[Int](x - 1).flatMap(_ => stateFactorial.map(z => x * z))

rajeevprasanna / GridChallenge.scala

Last active September 20, 2016 05:39

	//Problem : https://www.hackerrank.com/challenges/angry-children

	// Algorithm :
	// Read input into 2D lists => List(List(x))
	// Sort every row of the matrix
	// Then iterate over every column, check for unsorted first column
	// break if we find unsorted column


	object Test extends App {

rajeevprasanna / Solution.scala

Last active September 18, 2016 13:31

Print the absolute difference between the two sums of the matrix's diagonals as a single integer.

	object Solution {

	def main(args: Array[String]) {
	val sc = new java.util.Scanner (System.in);
	var n = sc.nextInt();
	var a = Array.ofDim[Int](n,n);
	for(a_i <- 0 to n-1) {
	for(a_j <- 0 to n-1){
	a(a_i)(a_j) = sc.nextInt();
	}

rajeevprasanna / Main.scala

Created June 12, 2016 05:14

file io with akka streams

	import java.util.concurrent.ThreadLocalRandom

	import akka.actor.ActorSystem
	import akka.stream.{ClosedShape, ActorMaterializer}
	import akka.stream.scaladsl.{Sink, Flow, Source, FileIO, GraphDSL, Broadcast, RunnableGraph}

	import java.io.File

	import akka.util.ByteString

rajeevprasanna / Main.scala

Created June 10, 2016 16:34

Twitter stream listener

	import akka.actor.{ActorRef, ActorSystem}
	import akka.stream.scaladsl._
	import akka.stream.{OverflowStrategy, ActorFlowMaterializer}
	import org.reactivestreams.Publisher
	import twitter4j.{StallWarning, StatusDeletionNotice, TwitterStreamFactory, FilterQuery}
	import twitter4j.{Status => TwitterStatus}
	import com.typesafe.config.ConfigFactory
	import twitter4j._
	import twitter4j.conf.ConfigurationBuilder

rajeevprasanna / TransformationBackend.scala

Created May 13, 2016 11:58

Simple akka actor cluster example

	import akka.actor.{RootActorPath, Actor, Props, ActorSystem}
	import akka.cluster.{Member, MemberStatus, Cluster}
	import akka.cluster.ClusterEvent.{CurrentClusterState, MemberUp}
	import com.typesafe.config.ConfigFactory

	/**
	* Created by rajeevprasanna on 5/13/16.
	*/
	object TransformationBackend {
	def main(args: Array[String]): Unit = {

rajeevprasanna / Boot.scala

Created May 9, 2016 07:09

Full source code explanation is available here : https://dzone.com/articles/building-rest-service-scala

	import akka.actor.ActorSystem
	import akka.http.Http
	import akka.http.model.{StatusCodes, Uri, HttpResponse, HttpRequest}
	import akka.stream.FlowMaterializer
	import akka.stream.scaladsl.Flow
	import akka.http.model.HttpMethods._
	import play.api.libs.json.Json
	import play.modules.reactivemongo.json.BSONFormats
	import reactivemongo.bson.BSONDocument

rajeevprasanna / WebsocketExample.scala

Created May 6, 2016 11:33

simple websocket example


	import akka.actor.ActorSystem
	import akka.http.scaladsl.Http
	import akka.http.scaladsl.model.ws.{TextMessage, Message}
	import akka.http.scaladsl.server.Directives._
	import akka.stream.ActorMaterializer
	import akka.stream.scaladsl.Flow
	import scala.concurrent.ExecutionContext.Implicits.global

	object WebsocketExample extends App {

rajeevprasanna / Main.scala

Created May 6, 2016 10:50

Sample supervision strategy example

	import akka.actor.SupervisorStrategy.{Escalate, Restart}
	import akka.actor._
	import scala.concurrent.duration._

	object Main extends App {
	val system = ActorSystem("supervisorStrategy")
	implicit val context = system.dispatcher

	import scala.concurrent.ExecutionContext.Implicits.global

rajeevprasanna / Main.scala

Created May 6, 2016 07:32

Simple message persistence example

	import akka.actor.{Props, ActorSystem}
	import akka.event.Logging
	import akka.http.scaladsl.Http
	import akka.http.scaladsl.client.RequestBuilding
	import akka.http.scaladsl.marshallers.sprayjson.SprayJsonSupport
	import akka.http.scaladsl.marshalling.ToResponseMarshallable
	import akka.http.scaladsl.marshalling.ToResponseMarshaller
	import akka.http.scaladsl.model.{HttpResponse, HttpRequest}
	import akka.http.scaladsl.server.RouteResult.Complete
	import akka.http.scaladsl.unmarshalling.Unmarshal

Rajeev Kumar kallempudi rajeevprasanna