noahlz

// See http://stackoverflow.com/questions/1052476/what-is-scalas-yield/1059501#1059501

// Compilation error is:
// [error]  found   : Seq[String]
// [error]  required: Option[?]
// [error]     child <- foo.children
// [error]           ^
// [error] one error found

noahlz

def divBy3(x: Int)  = x % 3 == 0
// divBy3: (x: Int)Boolean

def divBy5(x: Int)  = x % 5 == 0
// divBy5: (x: Int)Boolean

def divByAll(fns: List[(Int => Boolean)])(x: Int) = fns.foldLeft(true)((modZero, fn: (Int => Boolean)) => modZero && fn(x))
// divByAll: (fns: List[Int => Boolean])(x: Int)Boolean

val divBy3And5 = divByAll(List(divBy3,divBy5)) _

noahlz

(ns hello.core
  (:require [clojure.java.io :as io])
  (:import [java.net ServerSocket]))

;; Server
(defn receive-msg [socket]
  (.readLine (io/reader socket)))

(defn send-msg [socket msg]
  (let [writer (io/writer socket)]

noahlz

Scala can be a little obtuse. Yesterday I encountered something like this:

def foo(bar: Bar): Option[Bazz => Buzz => Blah]

It's a function that takes Bar and returns an Option boxing a function that takes a Buzz and returns a Blah. I think some clarifying parenthesis are in order, and probably should be required by the compiler.

When you see something like this:

noahlz

trait Color {
  def name: String
}

abstract class PrimaryColor(val name: String) extends Color
case object Red extends PrimaryColor("Red")
case object Blue extends PrimaryColor("Blue")
case object Yellow extends PrimaryColor("Yellow")

trait HasColors {

noahlz

Here's my idea of what goes in a run book for an application:

• On which servers it is installed
• Databases to which it connects (externally managed, not embedded)
• how to start/stop, i.e. actual command line or script to execute
• Scheduled batch jobs / EOD processes. Not the actual schedule, but when they generally run (EOD, overnight, etc)
• Where to find log files
• How to verify that it's actually running
• A screen shot of the login page and one or two application pages is helpful.

noahlz

Operations Team should not deploy a new software application to production unless the Development Team complies with the following minimum requirements:

Software Requirements

• Packaging: the application must conform to conventions for configuration, directory structure and run scripts:

  • Configuration
  • Deployment Build
  • Run script

• Reference Configuration: The reference configuration file included in the package must:

noahlz

package noahlz

import com.novus.salat._
import com.novus.salat.global._
import com.novus.salat.grater
import scala.util.control.NonFatal

case class Data(name: String, datums: Vector[Double])
case class MaybeData(name: String, datums: Vector[Option[Double]])
case class Datum(d: Option[Double])

noahlz

scala> val x  = 1 :: 2 :: 3 :: Nil
x: List[Int] = List(1, 2, 3)

scala> val y = 1 :: 2 :: 4 :: Nil
y: List[Int] = List(1, 2, 4)

scala> x union y
res1: List[Int] = List(1, 2, 3, 1, 2, 4)

scala> res1.distinct

noahlz

## Simple extension of the Chef tutorial for appending line(s) to the end of a cookbook
## Alternative to copying an entire cookbook just to add one line to a config file.
## (Apparently, partials are an alternative in Chef 11?
## http://stackoverflow.com/a/19167106/7507

file 'motd' do
  content "hello chef\n"
end

ruby_block "ensure sig to end of file" do