Viksit Gaur

I never had the privilege of meeting Steve Jobs. And yet, on hearing the news today, it felt like someone very close to me had died.

As someone I’ve followed from ever since I can remember – growing up listening to the stories of his showmanship and visionary designs, its hard to even remotely express the sense of loss I feel today.

Reading up on every book about him I could lay my hands on, watching liveblogs of new product announcements, and waiting with excitement at a WWDC or Macworld announcement – it almost feels like I actually knew him. And I think a large number of people from my generation share my feelings.

It is very rarely in a lifetime that you get to see someone like Steve Jobs accomplish the kinds of things he did – changing the very face of technology and entertainment as we know it. I’m so glad to have been in the valley to follow some of this first hand.

Here’s to the man who inspired an entire generation with his insane genius. And specially me.

Goodbye Steve. You’ll be missed.

I found this gem of a snippet today, and I rather agree with what it says!

“How solemn and beautiful is the thought that the earliest pioneer of civilization, the van-leader of civilization, is never the steamboat, never the railroad, never the newspaper, never the Sabbath-school, never the missionary — but always whiskey! Such is the case. Look history over; you will see.

The missionary comes after the whiskey — I mean he arrives after the whiskey has arrived; next comes the poor immigrant, with ax and hoe and rifle; next, the trader; next, the miscellaneous rush; next, the gambler, the desperado, the highwayman, and all their kindred in sin of both sexes; and next, the smart chap who has bought up an old grant that covers all the land; this brings the lawyer tribe; the vigilance committee brings the undertaker. All these interests bring the newspaper; the newspaper starts up politics and a railroad; all hands turn to and build a church and a jail — and behold! civilization is established forever in the land.

But whiskey, you see, was the van-leader in this beneficent work. It always is. It was like a foreigner — and excusable in a foreigner — to be ignorant of this great truth, and wander off into astronomy to borrow a symbol. But if he had been conversant with the facts, he would have said: Westward the Jug of Empire takes its way. ”

From this Wired article here, it looks like there’s a number that is part of the cyber command’s logo – 9ec4c12949a4f31474f299058ce2b22a. Well, its 32 characters long, and looks like a hash. Sure enough, a quick python check later of the organization’s mission statement with md5 results in,

import hashlib
>>> hashlib.md5("USCYBERCOM plans, coordinates, integrates, synchronizes and conducts activities to: direct the operations and defense of specified Department of Defense information networks and; prepare to, and when directed, conduct full spectrum military cyberspace operations in order to enable actions in all domains, ensure US/Allied freedom of action in cyberspace and deny the same to our adversaries.").hexdigest()
'9ec4c12949a4f31474f299058ce2b22a'

Voila!

I’ve been trying to figure out how best to serialize data structures in Clojure, and discovered a couple of methods to do so. (Main reference thanks to a thread on the Clojure Google Group here )

(def box {:a 1 :b 2})

(defn serialize [o filename]
  (with-open [outp (-> (File. filename) java.io.FileOutputStream. java.io.ObjectOutputStream.)]
    (.writeObject outp o)))

(defn deserialize [filename]
  (with-open [inp (-> (File. filename) java.io.FileInputStream. java.io.ObjectInputStream.)]
    (.readObject inp)))

(serialize box "/tmp/ob1.dat")
(deserialize "/tmp/ob1.dat")

This works well for any Clojure data structure that is serializable. However, my objective is slightly more intricate – I’d like to serialize records that are actually refs. I see a few options for this,

– Either use a method that puts a record into a ref, rather than a ref into a record and then use the serializable, top level map
– Write my own serializer to print this to a file using clojure+read
– Use Java serialization functions directly.

Thoughts?

My last post on the topic was creating a stack implementation using Clojure protocols and records – except, it used atoms internally and wasn’t inherently “functional”.

Here’s my take on a new implementation that builds on the existing protocol and internally, always returns a new stack keeping the original one unmodified. Comments welcome!

(ns viksit-stack
  (:refer-clojure :exclude [pop]))

(defprotocol PStack
  "A stack protocol"
  (push [this val] "Push element in")
  (pop [this] "Pop element from stack")
  (top [this] "Get top element from stack"))

; A functional stack record that uses immutable semantics
; It returns a copy of the datastructure while ensuring the original
; is not affected.
(defrecord FStack [coll]
  PStack
  (push [_ val]
	"Return the stack with the new element inserted"
	(FStack. (conj coll val)))
  (pop [_]
       "Return the stack without the top element"
	 (FStack. (rest coll)))
  (top [_]
       "Return the top value of the stack"
       (first coll)))

; The funtional stack can be used in conjunction with a ref or atom

viksit-stack> (def s2 (atom (FStack. '())))
#'viksit-stack/s2
viksit-stack> s2
#
viksit-stack> (swap! s2 push 10)
#:viksit-stack.FStack{:coll (10)}
viksit-stack> (swap! s2 push 20)
#:viksit-stack.FStack{:coll (20 10)}
viksit-stack> (swap! s2 pop)
#:viksit-stack.FStack{:coll (10)}
viksit-stack> (top @s2)
10