First Program in Haskell

Recently, I stumbled upon a new programming paradigm - functional programming. Rather than focusing on variables, we define functions that does something. Without much of theory, let us quickly see an example

Write a program that finds triplets (a, b c) such that a, b and c are sides of a right angle triangle with none of the sides is greater than 20. I tried to write programs in Java and in Haskell as well. Here is the code snippet

Java

public class RightAngleTuples {

public static void main(String[] args) {

printTuples();

}

public static void printTuples() {

for(int c = 1; c <= 10; c++) {

for(int a = 1; a <= c; a++) {

for(int b = 1; b <= a; ++b ) {

if(a*a + b*b == c*c && a+b+c == 24) {

System.out.println(a + ", " + b + ", " + c);

}

}

}

}

}

}

Haskell

 Prelude> let triples = [(a,b,c) | c <- [1..10], a <- [1..c], b <- [1..a], a^2 + b^2 == c^2, a+b+c == 24 ]

Prelude> triples

[(8,6,10)]

Initially it may appear that both the programs are different syntactically. But if you really see, while programming in an imperative languages, we need to think a lot of logic and variables (or memory location) that maintains the state of the program. It is programmers responsibility to keep the state sane. But in the case of functional programming, there is no concept of state. Everything is functions (obviously everything is logic).

If you are really interested to learn a new programming paradigm, i recommend Haskell. With my few hours of encounter with Haskell, i feel it changes one's thinking :-) and Learn you a Haskell for Great Good by Miran Lipovaca can be a great resource. (BTW, i copied the above example from the book and i promise that it is in fact last example that i will steal from the book). An heads-up: reading Haskell doesn't increase your value in job market :-), you cannot ask for 40% more hike but just improves your geeky quotient :-)

More stuffs on Haskell in coming weeks/months. Sharing never hurts :-) 

After a while things go real hard

It appears to me that i stopped blogging forever. I literally can't think what to write. It is over a month i tried to post something here. The past two months have been so engaging and lot of events. I felt that i lost touch and became irrelevant. I needed so much courage to write this post because i honestly think that every post should add value to me and at least to my eyes i should feel that my thinking is slightly getting better. This self imposed exile of keeping away from my blog was not so easy. I m back and i think i should be consistent.

Here comes the real learning. The manager typically delegates work sacrificing hands-on. Though the delegation helps and often needed when one moves up, being hands-on is equally important. I m not here to say that you need to strike balance as i think that such balance never exist in reality. All i m saying is "dont lose touch". Why?

Hands-on experience helps in better abstraction. Abstraction is more meaningful only if one is consistently gets his/her hands dirt. Without hands-on, the abstraction deviates from its course and it turns out to be a poor abstraction. The poor abstraction gives us meaningless decisions and from there the things go real hard. From empowerment, people move towards irresponsibility and abandonment without their own knowledge simply because they are far from reality and most of their decisions/thinking will become outdated.

Multiple Dimensions

What is 9460528400000000?

It is the distance traveled  by light in one year in meters. If the theory of big bang is true and if this universe started off from a tiny dot and still expanding till the moment we read this, what will be the size of universe. In which direction does it expand, may be in all possible direction. If you say the size of universe is infinite, how infinite is it? We tried to find the size of universe and we failed. And then we started to say "the size of observable universe"

Assume that we haven't invented numbers yet. How will you describe the size of universe? Having no number system is a dimension and having a number system is a dimension. You need both to depict or guess the size of universe. You need "no number system" dimension to say that the universe is massive and you need "number system" dimension to say or to give a feel of how massive is this universe. Each dimension has its own job of conveying something unique of the subject. And we can travel only certain level in each dimension. Assume that instead of sending light to measure distance, you decide to walk and count the number of kilometers. Beyond a point, even sending light and measuring the distance doesn't do well (as waiting time is more. If you send light, only your grandson can receive the light reflected from the subject) and you have to measure the light that is originated from the distant galaxy. There is clearly inherent limitation in each dimension and we have switch over to another dimension to visualize things (and to overcome the limitations of a dimension)

Unless the subject is caught in few dimensions, our understanding of the subject will be vague and limited. Multiple dimensions really help not only in finding the size of universe  (science) but also in solving general problems in life. :-)

Design Patterns - How to Learn

Most often we encounter people whom they call themselves as expert in design patterns. They start off with the discussion saying that they know Singleton pattern - knowing little bit of what is singleton and completely ignorant of why Singleton is needed. While design pattern helped experts to improve their productivity and the quality of software they write, it hasn't done anything to novice designers like us. Right away, let me say that it is not the problem with the design patterns. It shows that the way we learn design patterns isn't right.

Learning design patterns starts with getting hands dirt with abstraction, hierarchy, encapsulation and loose coupling. All these attributes do not come easy and they evolve over a period of time with imagination. We have to visualize how a solution is better than the other and if we can solve by writing code, it really helps us to understand deeper.

Keeping that mind, i started to put together series of puzzles on software design to improve my design knowledge - particularly on object oriented software design for quite sometime. I would say that this method is changing the way i think. If you also want to get your hands dirt, you can find puzzles tagged as "Design for Fun".

"Design for Fun".

Let me tell you, more puzzles are on the way.

Software Design Puzzle #8 - Manufacturing Soaps

Assume that you are an expert in manufacturing many varieties of soaps - bath soaps, detergent soaps and all soaps in the earth. You have a magic recipes of soap making right from procuring raw materials till manufacturing soaps and shipping to stores. There are many processes involved in soap making and there are various flavors for each process. And some of the processes are optional and specific types of soaps. For example, you know that you to have add a lot of scents for bath/toilet soap and lot of whitening material for detergent soaps. 

The puzzle is to design the soap manufacturing with lot of processes/steps and all these processes/steps are sequential meaning that one process cannot start until the previous processes are complete. For instance, the process of shipping cannot happen until you make soap and you cannot make soaps until you form soap base and you cannot start soap base without raw materials.

Can you design soap manufacturing process where one step depends on so many previous steps. To induce your thinking, let us assume that you have the following processes/steps

• Buy raw materials (can be different based on the soaps)
• Mix raw materials
• Form soap base
• Make soaps
• Package soaps
• Ship It

You are free to add more steps but the key is to come up with a process that can be changed dynamically based on soap types that are going to be invented in future :-)

Interesting Tools on Bytecode Manipulation

The last week, i got a chance to experiment on couple of bytecode manipulation APIs/tools and thought i can share my learning here.

Javassist is one of bytecode manipulation APIs that helps you to manipulate bytecode and it is simpler to use. I wrote a simple method profiler that takes class files as input and instruments the bytecodes in each method. Added, method start time, complete time and measured the time spent in the method. One good thing about Javassist is that you can directly add code written in Java that compiles on the fly while instrumentation. Seems like bytecode instrumentation is bit easier in Javassist. With Javassist, you can also do on the fly instrumentation during classloading phase.

Retroweaver is another bytecode manipulation tool that back ports the code compiled by Java 5 to Java 1.4. If you have written classes (or a third party classes/libraries) in Java 5 and if your production system still runs with Java 1.4/1.3/1.2, you may want to check out this tool. It is really cool to use latest APIs/libraries in old JVM. Retrotranslator is a similar tool.

Bytecode engineering seems to be very interesting.

Why Contemporary Leadership?

In the ancient times, when locomotive motor was not invented, people who could afford, traveled using bullock carts and the people who weren't able to afford a pair of horses and cart traveled by legs. After the invention of motor and after having undergone industrial revolution, people travel by cars or public transportation. The means of transport has changed but the travel hasn't (moving from one point to another point).

Today, many of the organizations are finding ways for transportation of their organizations from point a (current state) to point b (the transformation state) and they are ready to do anything that ought to be done. They are not ready to travel using bullock carts. I think criticisms and cranky jokes of obsessed Gen Xs on Gen Y are fading away and by now people who will be getting old in near future have to anyway deal with Gen Ys by their sheer numbers. If they continue to criticize, i think it is not going to help the organization at large. Any organization needs contemporary ways of brining in more effectiveness.

These days, the people who join workplace (predominantly often called as Gen Ys) are value conscious and by their virtue of exposure, they tend to make decisions based on how things affect them. We can't question and debate on their way of thinking because this thinking is not unique to Gen Ys. It is part of human evolution. The evolution says, the size of human brain shrinks but its processing power increase every day and the way a 22 year old youth thought 20 years back and the way in which modern day youth thinks varies (greatly?).

While we talk about culture, workplace ethics, work ethics or professionalism, we got to understand that those are things that were once practiced and if we get too much carried away (or adamant) with yesteryears, it will be living in the past or reliving the past and who knows we may fail utterly when we relive. Our thoughts, approach and the way we achieve the vision has to be contemporary. This has to be freshness.

While leading, we ought to be contemporary and forward looking taking good things of the past which just gives enough direction and propulsion needed for the escape velocity and to puts us into the orbit. 

Freshness, productive, creativity and innovation applies even for leadership.

Democratization of Organization

There are two ways of getting things done - in your own way, dictatorially and in the way others like. With the machines, you can be dictatorial meaning that you decide when the machine has to produce products. Switch on the power, boot up the machine, make sure that all parts work in unison and the product is produced. It is a continuous system where the output is predictable. But in the place where human beings are involved and the factor of motivation/passion more appropriate than fear, democratization or knowing what people have in their mind becomes absolute need. Human beings are discrete systems and they become quite unpredictable as mind and emotions are involved. 

There are two reasons why you democratize anything. First is due to the fact that you cannot make decisions or you don't feel responsible for something that is going to happen and the second reason is that you want to democratize to align your people towards the vision - may it be vision of a company or a country or the mankind. The first reason actually paves way to collective irresponsibility (like the climate change where everyone talks but no one does anything) and the second approach involves a lot hard work (likes of Mahatma Gandhi, Martin  Luther King). In order for effective democratization to become reality, first we have to accept that we can achieve it after a lot of failures. Initially, people tend to misunderstand the process of democratizing before understanding it completely which at the initial stage results to a lot of failure. After the initial failures and if you rally around your people during the failures, the democratization takes shape and becomes effective.

What are the signs of effective democratization? If you have at least few souls who give back far more than what they take back and if the ratio of number of souls that give back to the number of souls take back increases as the function of time, then you are staging yourself for better democratization.

Puzzle - Who is Knight and Who is Knave

This is a puzzle that i read in internet sometime last week and thought of sharing it here.

There is an island that has people who always speak truth (knight) or people who always lie (knaves). Unfortunately, you need find the way to the capital of the island. You are standing at the fork and there are two roads - left and right. There are three people, let us call them A, B and C, who are native of the island standing near the fork. You approach them, they tell you the following statements

Two of us are knaves, one of us is knight and the road in the left goes to the capital.

Will you be able to find which road goes to the capital - is it left or right? 

Simplification and Generalization in Problem Solving

You scatter toy towers of varying heights on the floor and ask some five old kid to arrange the towers in increasing order of heights. Most likely, he is going to knock of the puzzle. His first problem (and yours) will be understanding the problem - what needs to be done. Once he understands, he will complete the puzzles with your help here and there.After sometime, you ask him to sort toy circles in increasing order to circumference. Most likely he is going to finish off this taking lesser time than his previous. 

Both the instances are specialization of sorting - a basic algorithm that is known to human being. Human beings were sorting objects in life much before sorting algorithms were put forth. All those sorting were merely specializations and they work in specific scenarios but not all. Rather than saying it won't for all scenarios it is better to say that it was not tried having "all scenarios" in mind.

It is when we think about "all scenarios" we forget the specifics and the properties that is unique to the given problem and start to think about the "commonalities". When we think about "commonalities" we abstract ideas/concepts and bring many levels of abstraction based on the "commonalities". The specifics that are known at the time of abstraction forms as a boundary condition for abstraction. So, it is also very important to think widely about a specialization so as to make the abstraction more flexible & accommodative. Moving from specialization to a broader generalization is possible only when we simplify the problem domain and think about "many scenarios".

In order to understand the problem, you have to travel towards specialization and in order to solve it after understanding it requires simplification and generalization (and for achieving this you have travel further in time, by time i mean experience).

In next post, we will see some of the ideas on generalization from neuroscience's point of view.

Software Design Puzzle #7.2 - Thread Pools & Tasks

Please refer to previous two posts on the same problem - Implementing Thread Pools and Tasks. Here is the link for your convenience.

• Software Design Puzzle #7 - Thread Pools & Tasks
• Software Design Puzzle #7.1 - Thread Pools & Tasks

Yesterday, i added a requirement that i want to have a priority for tasks (a problem on data structures and algorithms). Today, i thought about another feature that gives a lot of flexibility (real OO design). In the above examples, we didn't talk much about the threads in thread pools. Can we try to make threads in thread pool dynamic entity - based on the need, the number of threads in thread pool should grow or shrink. Here are my next set of questions.

1. What are the design decisions that i should take so as to make thread pool dynamic.
2. How can i make threads, tasks, thread pool at the topmost level of abstraction and yet get many different concrete implementations.
3. How can i ensure that the code I am going to develop after two years (due to new requirements) doesn't affect my code now (seal the code from modification for new requirements)
4. How can i bring in hierarchy, levels of abstraction and modularity for better design?
5. Do i have any design patterns?