Preston Pham prestonph

System Design Cheatsheet

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

Basic Steps

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?

Common Options

-#, --progress-bar Make curl display a simple progress bar instead of the more informational standard meter.

-b, --cookie <name=data> Supply cookie with request. If no =, then specifies the cookie file to use (see -c).

-c, --cookie-jar <file name> File to save response cookies to.

Applied Functional Programming with Scala - Notes

1. Mastering Functions

A function is a mapping from one set, called a domain, to another set, called the codomain. A function associates every element in the domain with exactly one element in the codomain. In Scala, both domain and codomain are types.

val square : Int => Int = x => x * x

	def urlses(cl: ClassLoader): Array[java.net.URL] = cl match {
	case null => Array()
	case u: java.net.URLClassLoader => u.getURLs() ++ urlses(cl.getParent)
	case _ => urlses(cl.getParent)
	}

	val urls = urlses(getClass.getClassLoader)
	println(urls.filterNot(_.toString.contains("ivy")).mkString("\n"))

	/*******************************************************************************
	* Description:
	*
	* Gulp file to push changes to remote servers (eg: staging/production)
	*
	* Usage:
	*
	* gulp deploy --target
	*
	* Examples:

	import scala.annotation.{StaticAnnotation, compileTimeOnly}
	import scala.language.experimental.macros
	import scala.reflect.macros.whitebox.Context

	@compileTimeOnly("use macro paradise")
	class Extends[T](defaults: Any*) extends StaticAnnotation {
	def macroTransform(annottees: Any*): Any = macro Extends.impl
	}

	object Extends {

	import scala.collection.mutable.ListBuffer
	import org.scalacheck._, Arbitrary._, Prop._

	// a specs2 example showing that it works
	def e1 =
	forAll(distinctListOf[Int]) { ls =>
	ls.distinct === ls
	}.set(minTestsOk = 10000, maxSize = 1000)

	// distinct list of elements from a given arbitrary

	object Main extends App {
	AvoidLosingGenericType.run()
	AvoidMatchingOnGenericTypeParams.run()
	TypeableExample.run()
	TypeTagExample.run()
	}

	class Funky[A, B](val foo: A, val bar: B) {
	override def toString: String = s"Funky($foo, $bar)"
	}

	# set the base image to Debian
	# https://hub.docker.com/_/debian/
	FROM debian:latest

	# replace shell with bash so we can source files
	RUN rm /bin/sh && ln -s /bin/bash /bin/sh

	# update the repository sources list
	# and install dependencies
	RUN apt-get update \