teleported bits

Moving

2009-05-13T09:52:00.002+05:30

Hello reader, I am moving to wordpress: http://amitksaha.wordpress.com
All my blogging continues there.

Book Review: Embedded Linux Primer

2009-04-15T16:56:00.001+05:30

My review of Embedded Linux Primer: A Practical Real-World Approach is now in the stands - April, 2009 issue for Linux For You. Thanks to Linux For You and Pearson Higher Ed. for the review copy.

Quick Tip: Using the 'parsec' Haskell library

2009-04-09T13:43:00.002+05:30

You will have to do a sudo apt-get install libghc6-parsec-dev and sudo apt-get install libghc6-parsec-doc on Ubuntu/Debian systems if you are going to use the parsec library with ghc installed via apt-get

Once you have installed both, you should be able to use the library in your Haskell code and also view the library documentation.

Logo, Lisp and Me

2009-03-31T10:00:00.002+05:30

By the time I moved to a new school (Don Bosco School, Siliguri) in Grade 5, they had stopped teaching LOGO. So, my journey with computers in any form started with GW BASIC. So, I had no idea about what LOGO was except that it was fun. I did not have a computer so early and by the time I got it, I was too old (!!) for learning LOGO.

Some things have changed now, however. After 14 years have passed, I don't think that I am too old, any more! My 10 year old sister is learning LOGO in her 4th grade (Saint Joseph's School, Matigara) and I want to teach her to program LOGO on the computer. So I began my LOGO learning journey..

The first things I saw startled me:

Its a dialect of Lisp
Seymour Papert was one of the developers

To top it all:

"Logo is the name for a philosophy of education and a continually evolving family of programming languages that aid in its realization."
- Harold Abelson
Apple Logo, 1982

Never lose the child like wonder- said Randy Pausch in his last lecture. Well, I am 24 and I hope computers will continue startling me for many years to come!

Book Review: The Last Theorem

2009-03-29T08:24:00.003+05:30

I finished reading The Last Theorem, Arthur C. Clarke and Frederik Pohl. Its a story of Ranjit Subramanium and his life after he finds a proof to Fermat's Last Theorem

There is also a parallel storyline in the book which involves characters from other parts of the universe- Grand Galactics, One point fives and machine-stored creatures. The two storylines have common strings attached at various points and finally converges in the end with both Ranjit and Myra (his beloved wife) ending up as machine-stored long after their deaths.

My main motivation in reading this book was its fictional relationship to the theorem. Considering that, I am a tad disappointed as it doesn't really justify my choice as it has a somewhat cursory in its treatment of the theorem.

However, taking that out of the equation, this book is a enjoyable read as it takes you on a voyage in a solar sail and more. To the math lover's delight there are references to Sophie Germain and Lady Ada Lovelace.

For a detailed review of the book, please visit http://www.sfsite.com/03b/la292.htm

CS17 at Brown University: A great CS foundation course

2009-03-28T23:07:00.006+05:30

I just finished going through bulk of the lecture notes published as part of the CS17 course of Brown University.

The course begins by introducing functional programming via Scheme and moves on to OCaml in later stages. By introducing the two languages, the students get a flavor of a static and a dynamically typed language. An important point inferred is: static typing is not simply about prefixing the data type of the data during its declaration.

Just as a basic foundation course should, the course also introduces algorithmic analysis, Abstract Data Types or ADTs- the reason for calling them abstract is very well clarified with illustrations.

There are really great lecture notes in there and they are enjoyable too. If you are a CS student work the assignments out. If you are no more a student with at least a faint interest in good CS and if you haven't taken a look at this course, please do.

I would also be interested in knowing some more such delightful courses. If you know one, please let me know in a comment. (I am aware of SICP, and currently have planned a schedule for working through them)

SoM: Amnesia of Infancy

2009-03-27T22:05:00.006+05:30

(Image Source: http://www.medicirc.org/images/infancy_off.gif )

Marvin Minsky in in the prologue of his book- The Society of Mind, describes common sense as an amnesia of infancy, which makes human beings forget the way they learned to do simple things such as putting blocks together to form a tower.

Its insanely hard to tell more than a I don't know, when confronted with the How of knowing certain things:

Q: How do you know that if you fall, you get hurt?
A: I fell for the first ever time in my life and I got hurt, so I know that.

Q. How do you know that?
A. I learnt it the first time

Q. How did you learn and how did you remember?
A. I don't know much except that I, like most sane living beings, including animals have something called a brain which tells me these amazing things, which I now would classify under common sense.

Not perhaps the best example to prove my point. But, the idea is that most things that we know today, as adult human beings converges to a point, where all seems to be common sense, the origin of which we don't know.

Perhaps, that is amnesia of infancy.

The Music of Primes

2009-03-22T17:14:00.002+05:30

You really don't have to be a (wannabe) Mathematician to love prime numbers. Just browse through http://www.musicoftheprimes.com/ and you will have spent a very enlightening 45-60 minutes of your time.

Also, you might try to get hold of the book: http://books.google.com/books?id=3wtJP1qmnUcC

Learning Machines

2009-03-16T19:29:00.001+05:30

I just finished reading Computing Machinery and Intelligence, the oft-cited seminal work of Alan Turing.

The paper is the basis of the Turing Test that is a proposal for testing a machine's ability to think and hence demonstrate Intelligence, at par with Intelligent human beings.

Among the various issues discussed in the paper, (bulk of which I comprehended only slightly), section on Learning Machines interested me a lot. During a year's work (a year ago;now in coma) on Commonsense Reasoning, along with my supervisor, we were trying to devise or at least think of solutions to endow programs with simple commonsensical facts and figures- stuffs that "we, humans just seem to know", but the all conquering machines seem so dumb when confronted with them. The interesting point that is mentioned in the work is:

Instead of trying to make machines think or know like adult humans, we should rather think of making them think like small children, at birth and subject them to a learning process- filled with punishments and rewards, so that they learn during their life- so that they grow. They have a lifetime. In my words, I would call it as making machines aware of their immediate sourroundings, so that they learn, and gather exprience, as humans do.

On greater motivation and understanding, I might try my hand at giving back a bit to Wikipedia

Magical 6 Figure

2009-03-12T08:32:00.002+05:30

Howdy Readers! My blog hit the 100000 mark sometime today morning! Yay! I am also closing in on 500 posts.

Its been a great 3 years of blogging!

Quick Tip: Setting up LaTex editing with 'gvim'

2009-03-10T14:45:00.002+05:30

A year back, when I was using LaTeX for preparing my high-quality (at least visually!) technical reports, I used Kile. I liked it and was very happy with it.

I need to edit a .tex file again. However, instead of using Kile (which is a KDE program) on my XFCE destop, I decided to set up VIM for LaTex environment.

Turned out to be really simple:

Install the base latex compilers,etc. On Ubuntu, use sudo apt-get texlive-latex-base
Configure the Latex suite by following the excellent instructions here

And, you should be ready to go.

Book Review: The Hammer of God

2009-03-07T10:16:00.005+05:30

I finished reading my first Science Fiction work ever (Never too late :-))- The Hammer of God, Arthur C. Clarke.

Why did I choose this book, since frankly I had hardly any idea about what I was buying?
Well, I wanted to start reading Science Fiction (Why? Read the second point in Points for Style in How to Become a Hacker) and I had an upcoming 4-5 hour road trip coming up.

I was browsing through the books in the Science Fiction section and was reading the summary when the name of the asteroid- kali struck me. I mean, Kali? The Goddess of destruction, and being an Indian and a Bengali, I found it weirdly amazing. So I happily picked the book up, was excited to buy my first Science Fiction work ever and already had in mind the text I would write on the first page of the book.

It was an amazing read, taking exactly a week to finish and savour. How do I feel after reading my first Science Fiction?

Give me more!

DTrace on Linux

2009-03-04T22:40:00.005+05:30

Linux port of DTrace has been moving for some time now.

I just tried the latest bits from ftp://crisp.dynalias.com/pub/release/website/dtrace and the initial impression is we got really cool stuff (in the making here).

Besides, GCC, Kernel headers, you will need the following stuffs to compile and load the DTrace kernel module:

libelf-dev: Working with 'elf' files
zlib libraries: working with the zlib files
bison, flex

Once you have got them, extract the sources and do:

make all
sudo make install
sudo make load

If you do not see any error message, then the DTrace kernel module 'dtracedrv' has been correctly insrted.dtrace -l should display a long list of the currently available probes.

Let's try a simple DTrace one-liner.

This DTrace one-liner dtrace -n 'syscall:::entry { @num[probefunc] = count(); } will display the number of times a system call is invoked during the time its running. Press a C-c after sometime and you should see something like this:


amit@kubuntu904:~$ dtrace -n 'syscall:::entry { @num[probefunc] = count(); }'
dtrace: description 'syscall:::entry ' matched 329 probes
dtrace: buffer size lowered to 512k
dtrace: aggregation size lowered to 256k
^C


kill                                                              1
rt_sigpending                                                     1
readlink                                                          2
sigprocmask                                                       2
brk                                                               3
uname                                                             3
lstat64                                                           5
fcntl64                                                           7
sigreturn                                                         7
close                                                            11
open                                                             11
socketcall                                                       11
_llseek                                                          14
munmap                                                           15
rt_sigaction                                                     16
mmap2                                                            19
access                                                           27
rt_sigprocmask                                                   30
stat64                                                           54
fstat64                                                          69
setitimer                                                       230
writev                                                          397
time                                                            482
_newselect                                                      545
write                                                           709
futex                                                           727
ioctl                                                           754
poll                                                           1583
gettimeofday                                                   2212
read                                                           4878
clock_gettime                                                  5462

That's all for now. I just wanted to post my initial excitement :-)

Some points:

If your OS seems to hang after the DTrace command, and even a C-c/ C-d/ C-z won't help, then its possibly an issue with the terminal you are using. I had issues with gnome-terminal, xterm and ETerm. However, it works perfectly on KDE's konsole
If you are using Debian 5, you will possibly need to recompile your kernel for the zlib symbols in the kernel
If you are familiar with DTrace on Solaris, you must have noticed that I could use DTrace as non-root user, this is different from the way it works on Solaris. I shall try to explore more on this.

NetBeans Community Docs: 300!

2009-03-02T22:43:00.001+05:30

Hey all!

We at the NetBeans Community Docs have reached 300 documents! Wow! Exactly, 2 years back the program was started by James Branam!

Congratulations to all involved in the program! Thank You James for starting the program which have helped many a soul to do their bit for a great Open Source project.

A very big Thank You :-)

Quick Tip: 'Download' YouTube (or like) Videos, Linux only

2009-02-25T08:49:00.001+05:30

You watch videos on YouTube, Google videos, and all those FLV powered video sharing portals. You want to download it and save it for your later pleasure. Ofcourse, lots of desktop and online portals are available. Well, if you are on Linux (atleast; don't know about other Unix), you need none.

The video that you are currently viewing is on your Linux in a file: /tmp/FlashFOO (the FOO can be any random string. After the video is completely buffered, you just have to copy the file to your local disk for persistent storage. That is it.

You can watch as many you want and copy them too. Each of the Flash* files have a unique random character string.

Linux Kernel 2.6 compilation Guide, User Mode Linux (UML), Ext4 support

2009-02-21T18:12:00.004+05:30

When I wrote this guide 3 years ago, it was my first ever attempt at writing articles which I had yearned to start. I had to get bluetooth support on my Linux 2.4 kernel and the easier and better way out was to upgrade to a 2.6 series kernel. Hence the guide. Its still good. Let me know, if otherwise.

Today, I wanted to play around with the Ext4 filesystem and User Mode Linux. Hence I am recompiling a vanilla 2.6.28 kernel, the first time after I had written that article. I am reproducing it here with some modifications and the theme as compilation of a vanilla kernel, rather than the upgradation and spelling corrections specific to User Mode Linux (UML) and ext4.

The idea is to build a 'ext4' and a UML enabled kernel, then some newbie style playing with the UML and 'ext4' filesystem. I am using Debian 5.0 "Lenny" on VirtualBox (I don't have much to loose, that way :-))

Obtaining the kernel source code

Get the latest kernel source code (I am using 2.6.28) and extract it to a directory under your $HOME.

Kernel Configuration

You will need to enable the 'ext4' support under 'Filesystems' and also specify that we are building a UML kernel:

debian:/home/amit/kernel/sources/linux-2.6.28# make depconfig ARCH=um

debian:/home/amit/kernel/sources/linux-2.6.28# make menuconfig ARCH=um

Save the configuration.

Building the Kernel

Once the configuration is over, you can start the build process:

debian:/home/amit/kernel/sources/linux-2.6.28# make linux ARCH=um

After the build process is over, you will have a binary, linux which is the kernel just built for you with UML support.

Booting into UML

Before you can boot, you will need a UML root file system. You can either download one from here or build one yourself, or you may boot your host file system. I am using the root filesystem image for DSL provided in the earlier mentioned link:

./linux ubd0=./DSL-4.4-root_fs
Locating the bottom of the address space ... 0x0
Locating the top of the address space ... 0xc0000000
Core dump limits :
soft - 0
hard - NONE
Checking that ptrace can change system call numbers...OK
Checking syscall emulation patch for ptrace...OK
Checking advanced syscall emulation patch for ptrace...OK
Checking for tmpfs mount on /dev/shm...OK
Checking PROT_EXEC mmap in /dev/shm/...OK
Checking for the skas3 patch in the host:

.
.

and finally you will get a root# prompt. To ensure, that we are really in UML, cat /proc/cpuinfo :


processor : 0
vendor_id : User Mode Linux
model name : UML
mode  : skas
host  : Linux debian 2.6.26-1-686 #1 SMP Sat Jan 10 18:29:31 UTC 2009 i686
bogomips : 10643.04

Well, we just got started. You might want to try lots of other things. Networking, Jails, blah blah. Visit the UML homepage for more resources. Also, read the UML documentation in the Kernel source tree under Documentation/.

Trying Ext4

We will need to do some extra things to start playing around with 'ext4'.

We will have to: create a new kernel image, make the modules, install them and boot into the new kernel (as mentioned here). Once booted into the new kernel, try out some of the stuffs as in here

I tried one of the alpha releases of Kubuntu 9.04, which supports 'ext4'. It was pretty much blazingly fast.

Higher-Order Procedures

2009-02-18T18:57:00.005+05:30

Higher-Order procedures is my attempt to introduce the topic in an easy way. Please post your comments/suggestions here. (PDF)

Book Review: Programming Groovy

2009-02-02T22:47:00.001+05:30

I have zero experience with Groovy before this. However, I am well versed with the Java language and hence this review should be read from the point of view of a Java guy but a Groovy newbie. My goal in reading this book is get acquainted with the Groovy language and keep the knowledge in my sub-conscious mind so that I am ready when I need it :-)

Programming Groovy is a great starting point to the Groovy language and more so if you are already decently acquainted with Java . The whole book is divided into three parts, each part looking at different features of the language.

Part I: Beginning Groovy

As the name of this part suggests, in this part of the book, the author begins with instructions on how to go about setting up your system for Groovy development. Among other things, working with the Groovy shell is demonstrated.

Being well acquainted with Java, I skimmed over the chapters 2 and 3. Things are very familiar in these chapters. Chapter 4- Dynamic Typing talks about data types in Groovy and some other essential information of typing in Java world and its counterpart in the Groovy world. This chapter also introduces multi-methods. Chapter 5- Using Closures was the first major interesting roadblock for me. I intended to understand it fully and so I read this chapter and worked on it for a couple of times. Co-incidentally, I was also reading about closures in Common Lisp. You will need to understand at-least, what closures are and how they can be used- Sections 5.1-5.3 (as you will later see) that closures are widely used in Groovy. Most of the times, you will be passing a closure around to standard method calls in Groovy. So, understanding how a closure works is very useful. You may also want to read more about closures here. Chapter 6- Working with Strings, introduces the GString ( he he )- which are interpolated strings, and also talks a bit about the GString Lazy Evaluation Problem. Some other topics include: Groovy's own String Convenience Methods, and Multiline Strings. The last chapter in this part- Working with Collections talks about working with the usually available data structures: lists, maps and arrays, alongwith the convenience methods made available by Groovy.

Part I is over and I haven't yet learnt to take a User Input or is it assumed that I am a Java developer?

Part II: Using Groovy

Using Chapter 8: Exploring the GDK, looks at the extensions provided by the GDK to make the JDK more groovy.

In the next three chapters, the author will help you start using Groovy in your daily tasks, like Working with XML files, Databases (GSQL) and mixing and matching Groovy and Java.

Part III: MOPping Groovy

This part of the book looks at the implementation of the Meta-Object Protocol in Groovy and essentially builds upon it to present other very useful concepts such as Unit Testing and Mocking (where you are shown how to write Unit tests for your Java classes in Groovy), Groovy Builders and finally, at Creating DSLs in Groovy. This part can be classified as some serious and advanced Groovy and is a great collection of some very cool concepts in Groovy.

Overall, this book of is a great introduction to Groovy for the Java developer. I am not sure, how non-Java developer would benefit at all from this book, or for that matter Groovy.

Great work by the author and the whole team!

To learn more about the book, errata and discussions, please go to http://www.pragprog.com/titles/vslg/programming-groovy

Many thanks to O'Reilly UG program for providing with a review copy to BOJUG. This review is also published at the BOJUG blog at http://bojug.in/blog/?p=49

BOJUG Meet Pictures

2009-02-01T14:10:00.001+05:30

We had this month's BOJUG meet yesterday. Some pictures here at the fficial Blog post entry: http://bojug.in/blog/?p=45

WTF?

2009-01-28T16:08:00.001+05:30

...Perl, Some internal DSLs, Python, Java, Lisp, Groovy, Ruby, Lisp, Clojure

I read/write almost all of these everyday..WTF!

BOJUG Meet: January 2009

2009-01-27T18:49:00.001+05:30

We are meeting this Saturday, 31st January for our monthly meet. Details here at http://bojug.in/blog/?p=37

NetBeans needs more love?

2009-01-27T15:22:00.001+05:30

I am not looking to open a can of worms here. But this discussion here set me thinking: Does the world need more NetBeans love?

How often do we see that a Eclipse plugin is the way to go for most products, and we don't have the same for NetBeans? Why is Eclipse preferred over NetBeans when a choice needs to be made. The little that I understand of this business of FLOSS, NetBeans is as much a FLOSS product as is Eclipse.

What are the reasons- technical, political or cult?

Just to set the record straight: I am a completely NetBeans Guy- community member, committer and associated with the project for over a year now.

Sun Folks on the loose: Go Grab Them

2009-01-27T12:40:00.001+05:30

Unfortunately, I lost a lot of my Sun colleagues whom I knew directly or indirectly in last week's lay-off. The least I can do possibly is let the world know that great folks are available for hiring. Here's one: David Van Couvering (Ted's blog post about him).

Related post by Ted: http://www.sauria.com/blog/2009/01/22/suns-loss-your-gain/

Registers in VIM and other cool stuff

2009-01-26T17:49:00.003+05:30

In the VIM world, clipboards where your copied/cut text are stored are called registers. And, there can be multiple registers (which you can choose to name), where your text can be stored after you have performed a copy/yank on them. (See the section: Using multiple clipboards at http://jmcpherson.org/editing.html ).

Let's try this. Type in a couple of lines in VIM:

Now, select the lines and copy them to register 'r' using, "ry (in command mode).

Now type in the following VIM command: :echo @r. You should see the text that you have copied earlier:

This means that using '@r' you can use the contents of the register in your VIM scripts or plugins. We could also do some cool stuff, such as passing it to a GNU screen session, as you can see here. If you don't code in Lisp, no problem. You can use the script to setup your Python or Ruby or any other similar development needs, without any change.

Not working on 'odf4j'

2009-01-23T15:23:00.003+05:30

I have left working on the ODF Toolkit for Java: odf4j project 8 months back. I finally kicked myself to tell this here since I see a lot of visits to my blog with the label 'odf4j'.

Hence, please go ahead to http://odftoolkit.openoffice.org/ for all your queries.
Sorry for the late notice.