eugene-sy

/*
 * This file was generated by the Gradle 'init' task.
 *
 * This generated file contains a sample Scala library project to get you started.
 * For more details take a look at the Scala plugin chapter in the Gradle
 * user guide available at https://docs.gradle.org/5.0/userguide/scala_plugin.html
 */

plugins {
  // Apply the scala plugin to add support for Scala

gregberns

NOTE: This is an article by Chris Taylor, originally posted on his blog, but the blog was removed at some point. I resurected it from the WayBack Machine without the authors permission, but post it here for posterity's sake, so others may be able to find it.

Link: https://web.archive.org/web/20140222124650/http://chris-taylor.github.io/blog/2013/02/10/the-algebra-of-algebraic-data-types/

The Algebra of Algebraic Data Types, Part 1

by Chris Taylor

FEB 10TH, 2013

BalmungSan

import cats.Applicative
import cats.effect.IO
import fs2.Stream
import io.circe.Encoder
import io.circe.generic.semiauto.deriveEncoder
import io.circe.syntax.EncoderOps
import org.http4s.{EntityEncoder, MediaType}
import org.http4s.dsl.io._
import org.http4s.headers.`Content-Type`

BalmungSan

import cats.effect.IO
import io.circe.Encoder
import io.circe.generic.semiauto.deriveEncoder
import io.circe.java8.time.encodeZonedDateTimeDefault
import io.circe.syntax.EncoderOps
import org.bson.{BsonReader, BsonType, BsonWriter}
import org.bson.codecs.{DecoderContext, Codec, EncoderContext}
import org.bson.codecs.configuration.{CodecConfigurationException, CodecRegistries}
import org.mongodb.scala.MongoClient
import org.mongodb.scala.bson.codecs.{DEFAULT_CODEC_REGISTRY, Macros}

smarter

// Compiles with https://github.com/lampepfl/dotty/pull/4672
// ./bin/dotc -classpath "$(coursier fetch -p org.typelevel:cats-core_2.13:2.0.0)" out/fmap.scala
import cats._
import cats.implicits._

object Test {
  val fmap: [A, B] -> (A => B) => [F[_]] -> F[A] => (given Functor[F]) => F[B] = [A, B] -> (f: A => B) => ([F[_]] -> (fa: F[A]) =>  (given ev: Functor[F]) => fa.map(f))

  val addOne = fmap((x: Int) => x + 1)

Daenyth

Operation	Input	Result	Notes
map	F[A] , A => B	F[B]	Functor
apply	F[A] , F[A => B]	F[B]	Applicative
(fa, fb, ...).mapN	(F[A], F[B], ...) , (A, B, ...) => C	F[C]	Applicative
(fa, fb, ...).tupled	(F[A], F[B], ...)	F[(A, B, ...)]	Applicative
flatMap	F[A] , A => F[B]	F[B]	Monad
traverse	F[A] , A => G[B]	G[F[A]]	Traversable; fa.traverse(f) == fa.map(f).sequence; "foreach with effects"
sequence	F[G[A]]	G[F[A]]	Same as fga.traverse(identity)
attempt	F[A]	F[Either[E, A]]	Given ApplicativeError[F, E]

Geoyi

How to install virtualenv:

Install pip first

sudo apt-get install python3-pip

Then install virtualenv using pip3

sudo pip3 install virtualenv 

djspiewak

Thread Pools

Thread pools on the JVM should usually be divided into the following three categories:

1. CPU-bound
2. Blocking IO
3. Non-blocking IO polling

Each of these categories has a different optimal configuration and usage pattern.

kekru

• Open a webpage that uses the CA with Firefox
• Click the lock-icon in the addressbar -> show information -> show certificate
• the certificate viewer will open
• click details and choose the certificate of the certificate-chain, you want to import to CentOS
• click "Export..." and save it as .crt file
• Copy the .crt file to /etc/pki/ca-trust/source/anchors on your CentOS machine
• run update-ca-trust extract
• test it with wget https://thewebsite.org

nadavmatalon

double mapf(double val, double in_min, double in_max, double out_min, double out_max) {
    return (val - in_min) * (out_max - out_min) / (in_max - in_min) + out_min;
}