I thought of putting together some of my old mails and user group posting as blog entries, with some patches so that they are’ blogopatible’. They would have ended up on my blog, if I had a blog when I made these posts. I feel some of these are of lasting importance, at least with respect to the impressions they had on me.

All of these are personal opinions, probably more relevant in the context that they were originally written.

-----Original Message-----

From: James, Roshan

Sent: Friday, December 05, 2003 5:37 PM

To: MVP Mailing List

Subject: An Audience with Miguel

written in a hurry:

An Audience with Miguel

Hi, yesterday Pooja and I got to catch a part of Linux Bangalore, the annual Linux convention, and I thought that it would be nice to write to mvplist and share our experiences. We had missed the dates for the event and I was rather shocked at having missed a chance to see Miguel De Icaza in person.

Miguel, for those who don't know about him, is the creator of mc (the Midnight commander), Gnome (the rather popular open source desktop) and in recent days the lead for the Mono project. The Mono project is the only other major (when I say major here, it is not that I don’t know of dotGNU and other attempts, it is because I personally feel that Mono is more complete than those) .Net implementation outside of the Microsoft world. Mono runs on Windows as well as on Linux and probably other Unix flavors. This guy has been famous/notorious in the open source community for writing papers like 'Lets make Unix not suck' and has a rather 'misfit' personality for the typical religious ramblings of the free software types. In short this man has written his own windowing systems, his own .Net, his own enterprise servers and was running his own company called Ximian.

Ximian has been recently bought by Novell making Novell a major player in the open source world. Novell has also bought Suse - major Linux flavour and Novell seems to be on the path of becoming a significantly important open source company, along the lines of maybe Red Hat and such. However unlike Redhat and many of the 'Linux companies', Novell has a focus on delivering products rather than making Linux distributions and delivering them dirt cheap or free if they have to, to get into the market. So in short Miguel is as much a demi-god as our own Anders Hejlsberg, or Don Box.

The above paragraph was to set things in perspective. This is the mono website (http://www.go-mono.com/). Having been rather disappointed to have missed Linux Bangalore dates and missed Miguel, I happened to check their talk schedules by sheer accident around 11.30 yesterday. As fate would have it, there was a talk by Miguel, his last one, scheduled at 12.00. After a ~12km drive and some conversation with the registration counter we were at the IISC Bangalore venue – the last time I was here, I was attending the Microsoft Tech Ed.

One thing you notice up front as you enter is a big banner of Abdul Kalam, our president. The poster quotes him saying that it is probably not good to have important national software depending on proprietary solutions as proprietary solutions and highly dependant on the market that the vendors cater to and that sort of unreliability is probably not a good thing. And also that free software would really help a poorer country like ours as prices of commercial software are rather high. At least that was the message in spirit - don't think I have got any of his words right.

The crowd, as far as I could say was probably the same caliber as the technical crowd I usually get to interact with at UGs and various .Net technology events. Probably not as good in some respects - but there was this thing in the air that they were all up to 'something important'. Also one other thing that was noticeable was the set of demo computers setup, where people could sit down and try out many of the software that was being talked about in the talks.

Miguel's talk was at the main hall of the IISC venue (those who know the place will know what I mean). He was accompanied by Nat Friedman of Novell, a fellow mono-ist. What happened at the talk was something I wasn't prepared for. For those of you who have a mental image of Miguel by now, this guy is young, in his early twenties. He was carrying a digital SLR camera with a hefty lens and flash addons and was dressed in baggy jeans and black t-shirt. So was the other guy Nat. Now these guys hop on stage (literally), sit down on the floor - one of them rolls out a length of cable that he had wrapped around his neck the whole while. They pull out two laptops and they get a network setup between their systems and the presentation starts up.

The presentation showed of some parts of C# , web services, GTK# for windowing, GTK + for generating XML markup for the UI (and some jokes about how XAML is a copy of their own 6 year old idea) and more. These guys did the whole presentation sitting or lying down on the floor of the stage, sometimes editing the presentation right there in front of the audience, pulling jokes on each other and writing code the whole time for a full hour - and the whole thing was on their own Mono. Awesome.

After the talk Pooja and I met up with Miguel and introduced ourselves as being from the ‘dark side’ (He asked me if I was an ASP.Net developer because of all the questions I was asking from what otherwise seemed to be a relatively .Net ignorant audience. He was interested in the fact that I was an MVP.) and asked him if we could meet him sometime later, maybe over dinner or so. He was fine with that – that however was not to happen as his schedule did not allow him to. Various activities were planned for him for the whole of the next day (today, Friday) and he was going to flying on Saturday. He did promise to talk to our .Net user group the next time he is in India (expected to be in the second quarter of next year). I had to get back to office so I had to leave then; with the intention of returning for Jani's talk a little later in the evening.

I managed to sneak out of office again to attend the talk by Mr. Janakiram (I hope you know him - he heads Microsoft India's academic/university relationship program). Along with Jani was Mr. Gaurav Daga (he is a Program Manager of the famous Services for Unix team at Hyderabad; SFU won last years best open source software of the year award). Their venue didn't do any justice to their talk. Their talk was scheduled at one of the smaller halls and the crowd was so packed for the talk that I couldn't get close to the door of the hall. Jani and Gaurav as usual pulled a great show. They were talking about the new 'Unix' being built in windows ;) (Their demo was rather awesome: they took a Unix app ran it on windows literally, they wrote .Net code and exposed it as a web service, they built a proxy around the service and consumed the proxy as a COM component which was used by excel which was used to dump – did I miss anything?)  

All the while, from when he finished his talk, Miguel and his gang were there in the main lobby, showing off code or sitting or taking photographs or ready to talk to anyone at all about anything. When he was not doing that he would be sitting around in some corner with Nat typically typing away at a piece of code he was working on.

Since I couldn't get to listen to Jani at all due to the crowd and having driven the ~12km stretch in Bangalore traffic for the third time that day, I was walking around looking rather moody. Miguel then walks up to me, 'Microsoft dude', and gets our picture taken together. He kept calling me 'Microsoft dude' and he himself wanted to be called 'The Dude'; it was interesting talking to him.

I wanted to introduce Jani and Gaurav to Miguel and Nat after their talk. It was funny because on meeting Jani and Gaurav, Miguel seemed to freeze up a little bit - I think it's that Microsoft-effect. But on the whole they were nice folk. And Jani and Gaurav were good too. Jani mentioned how he wrote a wrapper around the 'Tk' widget library and called it a windows forms assembly and got to run some regular winforms code on Linux’

In retrospect, if I wanted to pick faults with the event I could and I could say that the organizing was bad, because the projector was shaky and the stage wasn't setup properly and the food was bad and all that and be complacent about the whole thing. But looking at the good side, you see guys who are probably the gods of their community actually sitting around with the developers showing off their code and laughing and talking rather that running off after a talk or sitting in a separate area. These are probably something's that we could learn from these folk. The number of people who Miguel touched that day and the number of people who will remember him are much more that those who will remember any of the speakers at technology forums where I have had the opportunity to speak or attend.

Miguel was different from my vision of the open source advocate. Probably because he was less of an advocate and more of a real programmer.

Miguel said that no they don't say that they are going to beat Microsoft or that Microsoft is going away or anything - which is normally common talk for OSI folk I have previously met. There is place for both he said. He said he has friends at Microsoft. He said that Dave Stutz is a good friend. We talked a little about Stallman and Free software. I asked him if he would be joining MS like Don Box offered and he said probably not. He would rather be doing his thing like this and be 'helping out the poorer countries'. He says they will keep on writing software, take good ideas wherever they find them and give it out as dirt cheap or free. There was this time when he said that 'they took out the GC and put in a toy GC in rotor and took out the JIT and put in a toy JIT in rotor - but the GC in Mono is your GC as much as its my GC' and he said that to Jani - 'its your as much as its mine and I would like to keep doing that'. There is this certain element of real sincerity which I find so missing in my work place and often at our technical seminars.

Free wheeling aside and sorry for all the typos and bad language in my writing, one thing that I probably miss from speakers and from many of our communities is that people hardly seem to be doing all that for themselves as much as for the community - I haven't seen anyone sit down and give all their time and energy to the community they are trying to foster. I don't see anyone on our side actually be there with the people and spread that sense of what they are doing - most of the audiences at our talks see us as speakers on podiums, rarely as people, we don't usually give them the room for that. I wish we could do that. And I wish that when we work on our user groups we can do it for the sense of community, rather than for the sakes of meeting numbers and budgets and revenue targets and stuff. I wish we all do this because we like our technology first - the Microsoft communities have never been able to do that the way these guys have. (This was probably rant, but reading this months later I feel that a lot of human touch is still missing in the communities. Somewhere the communities are built around a carrot culture and people who do things for carrots. Miguel has his carrots, but the way I saw his carrots were from a kind of passion that I personally feel in speakers I have known, myself being equally at fault. Something about what happened there that day felt like the spirit of those things I have thought about so much – hackerdom, the free hackers, the hacker ethic, mentor’s manifesto. Something is missing here and I am sure we can fix it because we have some extremely smart people who are so passionate about their technology)

I hope I have not tipped off any one by writing all this; this is probably something that could use some thought.

Cheers

Roshan

(Left to Right: Natt Friedman (Ximian/Novell of the Mono Project, cofounder of Ximian), Me, Miguel De Icaza (Ximian/Novell - author of Mono and other great feats of hackerdom, cofounder of Ximian), Gaurav Daga (Program Manager, Microsoft - Services for Unix Team), Pooja Malpani (CTS - programmer, Microsoft MVP .Net). This was taken at Linux Bangalore 2004, the annual Linux convention.)

(President’s quote put upon a hoarding at Linux Bangalore 2004)

This was recently posted on Miguel’s blog (there is more - go read the entry):
http://primates.ximian.com/~miguel/archive/2004/Apr-24.html

Jeff seems to like Cringley's statement of "The central point was that paying too much attention to Microsoft simply allows Microsoft to define the game. And when Microsoft gets to define the game, they ALWAYS win."

A nice statement, but nothing more than a nice statement, other than that, its all incorrect.

Microsoft has won in the past due to many factors, and none of them related to `Let them define the game', a couple from a list of many:

·         They leveraged their monopoly to break into new markets. The most discussed one is when they used brute force and anti-competitive strategies to get their products into new markets, but in some other cases they got fairly good adoption of their products with little or no effort: just bundle it with Windows: MSN messenger, Media Player.

·         Competitors were outmaneuvered or were incompetent (See HIgh Stakes No Prisoners).

·         People were sleeping at the wheel.

In 1993-1994, Linux had the promise of becoming the best desktop system. We had real multi-tasking, real 32-bit OS. Client and Server in the same system: Linux could be used as a server (file sharing, web serving), we could run DOS applications with dosemu. We had X11: could run applications remotely on a large server, and display on small machine. Linux quickly became a vibrant innovative community, and with virtual-desktops in our window managers, we could do things ten times as fast as Windows users! TeX was of course `much better than Windows, since it focuses on the content and the logical layout' and for those who did not like that, there was always the "Andrew" word processor. Tcl/Tk was as good as building apps with QuickBasic.

And then Microsoft released Windows 95.

·         A few years later, everyone is talking components: Netscape is putting IIOP on their client and server (ahead of their time, this later became popular as web-services on the browser); Xerox ILU; Bonobo; KParts; the Borland sponsored event to build a small component system that everyone agrees with; language bindings are at their top.

The concensus at that time? Whatever Microsoft is doing is just a thin layer on top of COM/DCOM/Windows DNA which to most of us means `same old, same old, we are innovating!'.

And then Microsoft comes up with .NET.

Maybe, sometimes, rarely, one man can change the world – or at least make a significant dent.

Iterators in Ruby (Part - 1)

Warming up to using Iterators (Part 2)
< I am yet to write a part 3 >
SICP, Fiber api and ITERATORS ! (Part 4)

I had a look at the implementation of iterators in C#. What follows is based on code generator I have seen on the C# Whidbey post PDC release. Things might have changed by now as things are moving to technology preview phase.

This is example code that is present in MSDN:

// yield-example.cs

using System;

using System.Collections;

public class List

{

    public static IEnumerable Power(int number, int exponent)

    {

        int counter =0;

        int result = 1;

        while(counter++ < exponent)

        {

            result = result * number;

            yield result;

        }

    }

    static void Main()

    {

        // Display powers of 2 up to the exponent 8:

        foreach(int i in Power(2, 8))

            Console.Write("{0} ", i);

    }

}

Notice the introduction of a nice little ‘yield’ keyword? The behavior of C# iterators in this context is a lot like ruby iterators that I have been talking about in previous articles. Knowing a little about the state management requirements for iterators and the fact that the CLR is stack based, how are iterators implemented in C#?

The implementation of iterators in C# is not driven by the CLR in any way, it is completely implemented in the language as a compiler construct.

Let me explain what the compiler tries to do – the compiler examines the function that does the yield

    public static IEnumerable Power(int number, int exponent)

    {

        int counter =0;

        int result = 1;

        while(counter++ < exponent)

        {

            result = result * number;

            yield result;

        }

    }

Lets just ignore the yield statement for now and look at the method as thought it contained only a loop. It would basically look like this:

There is Dylan playing somewhere in my head, and some things feel crushed:

Though I know that evenin's empire has returned into sand,

Vanished from my hand,

Left me blindly here to stand but still not sleeping.

My weariness amazes me, I'm branded on my feet,

I have no one to meet

And the ancient empty street's too dead for dreaming.

(Tambourine Man)

Have you ever listened to Dylan? Actually heard the visions of what could have been move by you? Probably not, not many people like to listen.

Then take me disappearin' through the smoke rings of my mind,

Down the foggy ruins of time, far past the frozen leaves,

The haunted, frightened trees, out to the windy beach,

Far from the twisted reach of crazy sorrow.

Yes, to dance beneath the diamond sky with one hand waving free,

Silhouetted by the sea, circled by the circus sands,

With all memory and fate driven deep beneath the waves,

Let me forget about today until tomorrow.

Hey! Mr. Tambourine Man, play a song for me,

I'm not sleepy and there is no place I'm going to.

Hey! Mr. Tambourine Man, play a song for me,

In the jingle jangle morning I'll come followin' you.

Sometimes, the closed world of the bit and baud seems to be the only reality that matters and somewhere it cajoles you into believing in a certain brotherhood of those who seem to understand it. And then again sometimes not.

And do you listen to Simon and Garfunkel?

When you're down and out, When you're on the street
When evening falls so hard, I will comfort you
I'll take your part, when darkness comes
and pain is all around,
Like a bridge over troubled water, I will lay me down
Like a bridge over troubled water, I will lay me down

(Bridge over Troubled Waters)

I downloaded and tried the new programming language Groovy today. In short groovy is like having Ruby on JVM. Maybe only better, because, it now has the power of the whole JVM to leverage. This is the homepage:

http://groovy.codehaus.org

The language is a stunner.

There is a lot of neat language design going on here.

http://wiki.codehaus.org/groovy/BlocksAndClosures

Imagine something like Ruby actually being available to code JSP, beans and what not in the Java world.

Being from the .Net background, I wish this was being done for the CLR. Imagine the power to the multi language support of the CLR brought into something like Ruby. For now I am content with gaping at features like this:

def counter(a)

{

      c = a;

      x = {c +=1; c};

      x

}

a_counter = counter(0)

b_counter = counter(20)

println(a_counter())

println(b_counter())

println(a_counter())

println(a_counter())

println(b_counter())

This actually works. Real closures!
If you are a lost C or VB soul, what is happening is that the function/method called counter() creates and returns a closure called x. A closure is a block of code that maintains state and scope based access to its variables. So closure x has the maintains state and has access to the variables of the method counter().

a_counter and b_counter are instance of the closure in the counter() method, that live after the invocations to the counter() method has exited. You can see that state is maintained between calls as the value of ‘c’ is incremented in each successive call.  

This is way ahead of languages like C# which are just grappling with their implementation of yield. This is of course not to blame the C# team, because admittedly the concept of programming with closures is yet to hit ‘the masses’

Groovy seems to do a whole pile of exciting things that Ruby can do

·         Closures

·         Iterators and Blocks

·         Regular expressions

·         Flexible collection types

·         Dynamic Method Invocations and types

I haven’t seen any mention of continuations, extendible classes, mixins and the like yet.

Of course, being on the JVM is slow and implementing a lot of features like the ones above, accounts for expensive constructs, which make the language even slower. However for most scripting language speeds, it should be acceptable.

What I think is more important is that languages of Ruby stature are being implemented on popular OO virtual machines. This is a sign for a possible trend in the future – a good one. It will be interesting times ahead when we have dynamic languages and functional languages move onto popular VMs.

I really like C and I think that simplicity is a feature (EricGu), however there is a real wealth of possibilities to be gleaned if constructs that have long been available only to students and researchers actually hit popular programming.

I am excited about the possibilities of a Ruby like implementation under .Net. Python is already getting there with Jim Hugunin and his IronPython.

Here are the folk behind Groovy:

http://groovy.codehaus.org/team-list.html

If you enjoy programming in Ruby or in a language that supports lists, iterators, closures etc, you might enjoy Groovy. It is still under development, so there might be things that are missing. You will also have to get the JVM.

This is a Wish List for Ruby. Ruby is an excellent language, however here are some small things that I would like to see added to Ruby:

• Threading
  I wish ruby had real threads. The threading support currently provided is really sad. If Rite could actually have OS threads as Ruby threads, like in the .Net framework it would be awesome, instead of doing them as interpreter threads. Write now doing any sort of meaningful multithreaded application in ruby is meaningless.
  
  
• C/C++ style operators
  I wish ruby had ++, -- operators. They really do not contribute to unmanageable code and on the whole are nice things to have.
  
• Use of Curly Braces { }
  I wish that Ruby would let the usage of curly braces to define blocks of code other than just parameter blocks that receive yield results. I would like to use {} to enclose methods, classes, if statements, loops etc.
  
  Write now code that is written like:
  
  def func(a)
     [1,2,3].each {|n|
        if(n % 2 == 0)
           print “This is even”
         else
           print “Odd”
           print “Multiple of 3” if (n%3==0)
         end
     }
  end
  
  being very C-ish in my ways I would really like it if I could avoid all those clumsy ends.
  
  def func(a) {
    [1,2,3].each {|n|
      if(n%2 == 0)
        print “This is even”
       else {
           print “Odd”
           print “Multiple of 3” if (n%3==0)
       }
    }
  }
   
  These days since the Python bug has bitten a bit, I am warming up to the idea of scope by indentation.
  
  def func(a)
    [1,2,3].each |n|
      if(n%2 == 0)
        print “This is even”
       else
           print “Odd”
           print “Multiple of 3” if (n%3==0)
  
  This actually looks quiet nice, but it may not be a good think to have because such code often tends to get messed up real bad when you copy paste it around and spoils the indentation.
  
  
• Better Win32Ole libraries
  This is something that I must have. I use scripting to be able to talk to WMI (Windows Management Instrumentation).
  
  The libraries that Ruby ship for this is really sad. Very unstable. At the time of this writing the current Ruby distribution has removed the win32ole libraries from Ruby. I hope they will come back, stabler.
  
  The reason why Win32Ole is important to me is that it is the mechanism used to talk to WMI and WMI can let you some really awesome stuff.
  
  WMI Primer on MSDN
  
  
• Auto Initialization of variables
  When I write code like this
  
  sum = 0
  10.times{|n| sum = sum + n }
  
  I wish I need not have to initialize ‘sum’. I wish there was some unambiguous way of saying that ‘I know sum hasn’t been defined before, so please use its initial value as ’. I would just like to be able to say 10.times {|n| sum = sum + n } and things should just work, assuming that sum gets initialized as 0. I wish there was some shorthand hand initializing a variable for its first appearance in an expression.
  
  Like I could probably replace:
  
  sum  = 0
  prod = 1
  10.times {|n| sum = sum + n; prod = prod * n }
  
  with
  
  10.times {|n| sum = sum<0> + n; prod = prod<1> + n; }
  
  or better if I had support for C++ style operators, I could write
  
  10.times{|n| sum<0> += n; prod<1> *= n; }
  
  
  
•  Run on .Net
  I wish ruby could run on .Net. There are python variants that run on Java and now Python is coming up for .Net (IronPython). Imagine the power of having the flexibility of Ruby with the power and expanse of the .Net framework.
  
  Maybe more work needs to be done before this is possible.
  
  
•  Currying of Methods and Partial Evaluations
  I wish I could have currying/partial evaluation possible for ruby methods.
  In many functional languages, functions are defined like this:
  
  - fn add x y = x + y
  > int -> int -> int
  
  Consider the ML like code above. The first line I have defines a function called ‘add’ that takes x and y and does x+y. The second line is what the interpreter echoes back to me about the function.
  
  It is simply is trying to say that the method consumes two integers and produces an integer. The two integers how ever are not used up at one go, rather, they are used up sequentially. First the integer x is taken and bound to the function and then the value y.
  
  By being able to do that, we can define other function instances of add that have one of the variables bound.
  
  - fn add10 = add 10
  - fn add5 = add 5
  - add10 2
  > 12
  - add5 2
  > 7
  
  This shows off some very powerful features of what currying can do. Here add10 and add5 are created as new functions, but with the value of x substituted as 10 and 5 respectively. Now we can treat add10 and add5 as proper functions that take only one parameter. 
  
  
  What these languages let us do is that we can apply a subset of the parameters of a function and created a curried or partially evaluated function instance. Such an instance can, if the runtime is optimizing enough, already do all the processes possible in the code upfront. Whenever the remaining parameters are supplied, it could just go on to complete the operations.  

Imagine that the method we were calling is this

fn mult x y = 10 * x * y

and then we wish to do

mult 10 2

mult 10 3

mult 10 4

 

These calls will now cause it to do 10 * 10 * 2, 10 * 10 * 3 and 10 * 10 * 4

However if we could partially evaluate a function we could say

 

fn mult10 = mult 10
mult10 2

mult10 3

mult10 4

 

When mult10 is created it is already evaluated to being “100 * y”. So, subsequent calls would cause it to do only 100 * 2, 100 * 3 and 100 * 4.

 

To add this sort of support to Ruby will have to bring large changes to the language. A simpler implementation would be to create a method object (yes that’s possible in Ruby) and also a hash of the partial list of parameters. The call itself could be formally executed only when all formal parameters are satisfied by the parameter hash table collection.

 

If you are still reading this might interest you:

http://www.svendtofte.com/code/curried_javascript/

Whew!

Well, that’s about it for now. But as you can see most of what I am asking for here are simple things and superficial changes. I would however really like to see the win32ole, threads and ++ operators in Ruby, even if none of the others work out.

Matz, (Yukihiro Matsumoto), the creator of Ruby is planning to introduce some significant changes to the language and more importantly going to get it running off a formal virtual machine that he is writing for Ruby called Rite.

Here are some of the plans for Rite and Ruby:

http://www.rubygarden.org/ruby?Rite

I found this on one of the websites, this is about how Matz wanted to work on Rite:

http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/76588
|* will Rite be developed publicly.. Or will you keep it souce secret?

From my experience and observation, an open source software needs to

have running code before the ball rolling to success.  I think I need to work alone until the first running version.

|* still use Ruby license scheme?

It will be open source software for sure.  License terms may be

changed.

|* do you need help?  Say what we should do and we will do it

This is very important.  Listen carefully.

From the reason I stated above, I feel like I will work alone.

But if someone shows his talent, and comes up with his own _good_

implementation of new Ruby earlier than me, and if he is willing to

contribute his code, and if he allows me to hack and chop his code to

make it "Rite", I will name it "Rite".  And he will be honored for ever.

An old Time magazine article on Bill Gates:
In Search of the Real Bill Gates

http://www.time.com/time/gates/cover0.html

A write up on Ruby by Matz himself:
The Ruby Programming Language

http://www.informit.com/articles/article.asp?p=18225&seqNum=2
The following is the outcome of a simple longest-word search program over
      /usr/share/dict/words (409067 bytes). These were tested on my Pentium-200MHz
      Linux machine.

Groovy programming language, reputed to be a lot Ruby like:
http://groovy.codehaus.org/

Groovy is a new agile dynamic language for the JVM combining lots of great features from languages like Python, Ruby and Smalltalk and making them available to the Java developers using a Java-like syntax.

(Groovy Entry)

Codehaus

Finally a project site that encourages the need to commercially use projects

http://codehaus.org/

The Codehaus differentiates itself from other similar efforts in several ways. The Codehaus places a firm priority on the production of useful code, and less on non-coding exercises such as voting, committee-forming and proposal-writing. Each project is provided autonomy to organize as it wishes and to address its own customer concerns and requirements directly. Codehaus is not entirely open to any and all projects. Projects must be sponsored or introduced through an informal manner by an existing haus-member and deemed to be "interesting".

Codehaus aims to support commercially useful projects, and thus does not sponsor or assist with projects licensed under the GPL or other business-hostile licenses.

Structure and Interpretation of Computer Programs (SICP)

If you are a fresher or are getting started on programming, or like thinking about programming I highly recommend reading the SICP.

http://mitpress.mit.edu/sicp/

"I think that it's extraordinarily important that we in computer science keep fun in computing. When it started out, it was an awful lot of fun. Of course, the paying customers got shafted every now and then, and after a while we began to take their complaints seriously. We began to feel as if we really were responsible for the successful, error-free perfect use of these machines. I don't think we are. I think we're responsible for stretching them, setting them off in new directions, and keeping fun in the house. I hope the field of computer science never loses its sense of fun. Above all, I hope we don't become missionaries. Don't feel as if you're Bible salesmen. The world has too many of those already. What you know about computing other people will learn. Don't feel as if the key to successful computing is only in your hands. What's in your hands, I think and hope, is intelligence: the ability to see the machine as more than when you were first led up to it, that you can make it more."

Alan J. Perlis (April 1, 1922-February 7, 1990)

Last night we did it again.

We went for this movie (50 First Dates) and came home feeling a little giddish. I was feeling a little giddish before the movie after nearly having my head ripped off sitting on a Torra Torra, in a fair in Bangalore.

So after the movie and the drive back home, what do we decide to do, like the nice normal people we are? We decide that we need to drink coffee at 12am and discuss programming. So we head off to Leela Palace where there is a late night Barista.

Something about the way coffee affects my head, when drunk late at night, especially after a movie needs some investigation. Sidharth was my comrade is arms, or rather comrade in coffee. So what do we do? we go there and sit down and drink coffee and I start off on SICP (Structure and Interpretation of Computer Programs) which I have been postponing for several years now.

I think part of why I was so adamant about starting out on SICP in the middle of the night is that I feel life (like usual) isn’t going anywhere. It turns out that a lot of smart people at various Universities decided that I was wasn’t smart enough to warrant a formal higher education in Computer Science and the place I want to be the most, doesn’t seem to want me around because of some technicality (for the fifth time). So since life wasn’t going anywhere, I figured I’d just have teach myself the things I want to know, my own way.

A little fast-forward in time and what finally ends up happening is that Sidharth and I end up talking about a certain MSDN article.

Implementing Coroutines for .NET by Wrapping the Unmanaged Fiber API

http://msdn.microsoft.com/msdnmag/issues/03/09/CoroutinesinNET/default.aspx

We ended up in a rather (heated) philosophic discussion about how iterators could be implemented, till 4am, which is what this blog entry is about.

If you have been reading about iterators in my previous blog entries

Iterators in Ruby (Part - 1)

Warming up to using Iterators (Part 2)

Then the idea is probably growing on you already. What Sidharth and I did is put in some thinking about how iterators could be implemented. This entry is going to break the logical flow of these two articles, but I am letting it be. I will probably have a part 3 post that will bridge the gap between Parts 1 and 2 and what I am going to say here about iterators.

Also, like a lot of things on this blog, I am not an authority on the subject so I am just guessing at how these things actually work.

Iterators

The thing about iterators is that there are two functions involved that have to maintain execution state at the same time. So example when a function calls another function, the caller is frozen and the callee executes – so the caller maintains execution state during the run time of the callee.