stettix

Things I believe

This is a collection of the things I believe about software development. I have worked for years building backend and data processing systems, so read the below within that context.

Agree? Disagree? Feel free to let me know at @JanStette. See also my blog at www.janvsmachine.net.

Fundamentals

Keep it simple, stupid. You ain't gonna need it.

gravitylow

If you are getting this in gdb on macOS while trying to run a program:

Unable to find Mach task port for process-id 57573: (os/kern) failure (0x5).
 (please check gdb is codesigned - see taskgated(8))

1. Open Keychain Access
2. In menu, open Keychain Access > Certificate Assistant > Create a certificate
3. Give it a name (e.g. gdbc)

adriaanm

// originally by @SethTisue, see http://stackoverflow.com/questions/40622878/how-do-i-tell-sbt-to-use-a-nightly-build-of-scala-2-11-or-2-12/40622879#40622879
resolvers += "nightlies" at "https://scala-ci.typesafe.com/artifactory/scala-release-temp/"                           
scalaVersion := {
  val propsUrl = new URL("https://scala-ci.typesafe.com/job/scala-2.12.x-integrate-bootstrap/lastSuccessfulBuild/artifact/jenkins.properties/*view*/")
  val props = new java.util.Properties
  props.load(propsUrl.openStream)
  props.getProperty("version")
}
scalaBinaryVersion := "2.12"

jdegoes

-- A sequential series of parallel program fragments in `f`:
type SeqPar f a = Free (FreeAp f) a

liftFA :: forall f a. f a -> SeqPar f a
liftFA = pure >>> pure

liftSeq :: forall f a. Free f a -> SeqPar f a
liftSeq fa = foldFree fa liftFA

liftPar :: forall f a. FreeAp f a -> SeqPar f a

DeLaGuardo

;; Enable ligatures without prettify-symbols

(provide 'add-pragmatapro-symbol-keywords)

(defconst pragmatapro-fontlock-keywords-alist
  (mapcar (lambda (regex-char-pair)
            `(,(car regex-char-pair)
              (0 (prog1 ()
                   (compose-region (match-beginning 1)
                                   (match-end 1)

vasanthk

System Design Cheatsheet

Picking the right architecture = Picking the right battles + Managing trade-offs

Basic Steps

1. Clarify and agree on the scope of the system

• User cases (description of sequences of events that, taken together, lead to a system doing something useful)
  • Who is going to use it?
  • How are they going to use it?

runarorama

sealed trait Interact[A]

case class Ask(prompt: String)
  extends Interact[String]

case class Tell(msg: String)
  extends Interact[Unit]

trait Monad[M[_]] {
  def pure[A](a: A): M[A]

pchiusano

trait ConsoleAlg[F[_]] {
  def readLine: F[Option[String]]
  def printLine(line: String): F[Unit]
}

trait Console[+A] {
  def run[F[+_]](F: ConsoleAlg[F]): F[A]
}

object Console {

nevang

import spray.json._
import reactivemongo.bson._
import reactivemongo.bson.handlers.{ BSONReader, BSONWriter, RawBSONWriter }
import scala.util.{ Try, Success, Failure }
import org.apache.commons.codec.binary.Hex
import org.joda.time.format.ISODateTimeFormat
import org.joda.time.{ DateTime, DateTimeZone }
import java.nio.ByteBuffer
import org.jboss.netty.buffer.ChannelBuffers

jimbojsb

Step 0:

Get Homebrew installed on your mac if you don't already have it

Step 1:

Install highlight. "brew install highlight". (This brings down Lua and Boost as well)

Step 2: