devsprint

# to install the latest stable version:
brew install scala --with-docs

# to install scala-2.10.0:
brew install https://raw.github.com/gist/4456110/scala.rb --with-docs

# to switch versions (from https://github.com/mxcl/homebrew/wiki/External-Commands):
# brew switch scala 2.9.2
brew switch scala 2.10.0

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slow

This bash script offers quick shortcuts to simulate slower network connections. It is useful when you need to simulate a wireless network on a Linux network server, especially when you are using a virtual machine guest on your local machine or in the cloud.

slow 3G                   # Slow network on default eth0 down to 3G wireless speeds
slow reset                # Reset connection for default eth0 to normal
slow vsat --latency=500ms # Simulate satellite internet  with a high latency
slow dsl -b 1mbps         # Simulate DSL with a slower speed than the default

slow modem-56k -d eth0 # Simulate a 56k modem on the eth1 device. eth0 is unchanged.

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Introduction to Kafka

Kafka acts as a kind of write-ahead log (WAL) that records messages to a persistent store (disk) and allows subscribers to read and apply these changes to their own stores in a system appropriate time-frame.

Terminology:

• Producers send messages to brokers
• Consumers read messages from brokers
• Messages are sent to a topic

devsprint

import spray.json._
import spray.http.HttpBody
import spray.httpx.marshalling._
import spray.httpx.unmarshalling._
import spray.http.MediaTypes._
import spray.routing.directives._
import spray.routing._
import spray.http._
import spray.json.DefaultJsonProtocol
import spray.httpx.SprayJsonSupport

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object ServerSparkContext {

  private[this] lazy val _sqlContext = {
    val conf = new SparkConf()
      .setAppName("....")
    val sc = new SparkContext(conf)

    // TODO: Bug in Spark: http://stackoverflow.com/questions/30323212
    val ctx = new HiveContext(sc)
    ctx.setConf("spark.sql.hive.convertMetastoreParquet", "false")

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Advanced Functional Programming with Scala - Notes

Copyright © 2017 Fantasyland Institute of Learning. All rights reserved.

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