akirillov’s gists

akirillov / DockerShortcuts.md

Created June 29, 2018 18:51

Docker shortcuts

Remove all images:

docker images --format "{{.ID}}" | xargs docker rmi

Stop and remove all containers:

docker ps -a --format "{{.ID}}" | xargs docker kill
docker ps -a --format "{{.ID}}" | xargs docker rm

akirillov / flatMapOptionImplicitConversion.scala

Created August 5, 2016 15:46

	//Let's say we have a list of Ints and function f from Int to Option:

	val list = (1 to 10).toList
	//List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)

	val f = (x: Int) => if (x%2==0) Some(x*2) else None
	//f: Int => Option[Int]

	//Now I'm going to apply f to the elements of the list and filter out empty results:
	list map f flatten

akirillov / ApplyExample.scala

Last active July 21, 2016 21:33

	/*
	for the test purposes function getValueAsync imitates some heavy lifting
	and returns type constructor parametrized by T (same for getValueOpt)

	in real life these could be different functions returning some type
	constructors like Option, List and Future which values
	should then be passed to a function which takes proper types

	Apply type class from cats has methods with a flavor like that:

akirillov / StackableTraits.scala

Last active July 13, 2016 08:41

Example of stackable traits in Scala

	type Payload = Array[Byte]

	trait Driver {
	def send(payload: Payload)
	}

	//a component which depends on Driver interface
	class Sender(val driver: Driver){
	def send(message: String) = driver.send(message.getBytes)
	}

akirillov / TailrecVsForeach.scala

Last active July 6, 2016 15:34

Comparison of tail recursive and imperative way of `map` implementation

	/*
	Test: tail recursive map vs imperative map
	*/
	object TailrecTest extends App{
	def measure[A](f: => A): (A, Long) = {
	val start = System.currentTimeMillis()
	(f, System.currentTimeMillis() - start)
	}

	/*

akirillov / RabbitDataFlow.scala

Created April 26, 2016 09:38

	object RabbitToRabbitFlow extends App {
	implicit val actorSystem = ActorSystem("rabbit-akka")
	implicit val materializer = ActorMaterializer()

	val config = ConfigFactory.load("application.conf")

	val sourceConnection = Connection(config.getConfig("source"))
	val targetConnection = Connection(config.getConfig("target"))

	val rabbitConsumer = Source.fromPublisher(sourceConnection.consume(config.getString("source.queue_name")))

akirillov / folds.hs

Created November 5, 2015 21:53

Library functions implementation with fold (from LYAHFGG)

	maximum' :: (Ord a) => [a] -> a
	maximum' = foldr1 (\x acc -> if x > acc then x else acc)

	reverse' :: [a] -> [a]
	reverse' = foldl (\acc x -> x : acc) []

	product' :: (Num a) => [a] -> a
	product' = foldr1 (*)

	filter' :: (a -> Bool) -> [a] -> [a]

akirillov / ad-hoc_polymorphism.scala

Last active October 20, 2015 17:57

Simple example of ad-hoc polymorphism in Scala

	//single parameter function for different types
	trait Size[A] {
	def size(a: A): Int
	}

	def size[A: Size](a: A): Int = implicitly[Size[A]].size(a)

	implicit object StringSize extends Size[String]{
	override def size(a: String): Int = a.length
	}

akirillov / cassandra.yaml

Last active August 29, 2015 14:25

Different combinations of listen/rpc addresses for Docker/EC2/hardware setups

	# Docker ===========================

	# MacOS specific command to connect from host machine: cqlsh `boot2docker ip`
	# Cassandra 1.2.9
	listen_address: 127.0.0.1
	rpc_address: 0.0.0.0

	# Cassandra 2.1
	listen_address: 127.0.0.1
	rpc_address: 0.0.0.0

akirillov / MonoidPML.scala

Last active August 29, 2015 14:19

Pimp my library with monoid operations on list

	package io.datastrophic

	trait Monoid[A]{
	def append(a1: A, a2: A): A
	def unit: A
	}

	object Monoid{
	implicit val IntMonoid = new Monoid[Int]{
	def append(a1: Int, a2: Int): Int = a1 + a2

Anton Kirillov akirillov