Language of the week: Haskell

Tristan Sloughter and I decided that this summer we would try learning a language each week in order to expand our knowledge of different programming languages. Our intent is to learn the lanuage well enough in order to do a simple to moderate program in the language. While I won't be able to go into detail about each language in this blog, I would like to highlight some key points of the language.

For the first language, we chose Haskell. I had used Haskell before, but it had been a long time. I had also just learned Ocaml from CS440, which shares some similarities to Haskell. For our project we decided to write the LZW algorithm, which is a simple text compression algorithm.

Haskell is well suited for this task, as the algorithm is a straight sequential process on the text, and since Haskell is a functional language, it allows for an easy implementation. The code is as follows.

The first thing we need to do is create table. Basically this is just defining what table is.

> type LZWItem = (Int, String)
> type LZWTable = [LZWItem]

After that we just need to create a table instance

> lzwTable :: LZWTable
> lzwTable = []

For the main implementation I broke the code up into 4 parts.

1. encString: main function that processes the string and takes care of the table

> encString :: String -> LZWTable -> String -> [Int]
> encString [] [] = []
> encString (k:ks) (w:ws)
> | inTable lzwTable ((w:ws)++(k:[])) = encString ks lzwTable ((w:ws)++(k:[]))
> | otherwise = addCode lzwTable ((w:k:[])++ks) : encString ks lzwTable (k:[])

Here we simply take a string as input, and process it character by character according to the LZW algorithm. If it is in the table, we continue by getting one more character, otherwise we add the string to the table.

2. inTable: this is just a little helper functiong for encString to check if the string is in the table
> inTable :: LZWTable -> String -> Bool
> inTable table str = [ tCode | (tCode,tStr)<-table, tStr==str] /= []

3. addCode: adds code to the table for a new substring > addCode :: LZWTable -> String -> Int
> addCode table (x:xs)
> | table ++ [(length(table)+1,x:xs)] /= [] = getCode table (take (length (x:xs)-1) (x:xs))

We add the new code, while getting the code for the previous string per the LZW algorithm.

4. getCode: gets the code from the table for a previous string in the table

> getCode :: LZWTable -> String -> Int
> getCode table str = head [ tCode | (tCode,tStr)<-table, tStr==str]

This simply just looks up the code from the table.

As you can see the implementation is very straightforward, relatively easy to understand, and compact. Doing this in any other(non-functional) language like C would definitely take a lot more code.

I am very happy with Haskell, as everything seems very intuitive and logical. When programming with it, you have alot of "Duh, that is so easy and simple" moments that you don't get with other languages.

When comparing Haskell with the other functional language I knew before this, Ocaml, I would have to say Haskell is better. To me, Haskell just has a better feel to it and seems to flow a little better than Ocaml. Either language is great though compared to C/C++, Java, Perl, etc.

One other cool trick I would like to quickly add about Haskell is infinite lists. For example, here is how you generate a list of every integer:

> numsFrom n = n : numsFrom (n+1)

If you are looking for a good place to start, I recommend the book, "Haskell: The Craft of Functional Programming". It is great at going through the key concepts of Haskell and showing you great examples of usage that can help you solve almost any problem.

For the curious, our next language is going to be Erlang.

Why I choose Windowmaker

For a very long time, I used Linux, just because it wasn't Windows. There were two things that made me actually enjoy Linux, so much so, that I feel deprived when I can't use a Linux machine(such as at work).

What were those two things? The first was Gentoo. I won't go into a rant about which distro is best, but Gentoo has worked for me very well.

The second reason, was Windowmaker. I had tried many other desktops, never thinking about Windowmaker, since it looks so ugly and useless. Finally, after getting tired of using Gnome and KDE and using g-this and k-that type of apps, I gave Windowmaker a try.

I was completely astonished. My productivity increased almost instantly. The speed in which you can switch desktops and maneuver to different apps all with just the middle button is a reason to use Windowmaker in of itself. I also enjoy the right click menu. Instead of having this fancy start menu and everything else that clogs most desktops, I have the full desktop to myself, and apps are only a right-click away.

I know I might not have the fanciest, latest gizmos like transparency, but is your amnesia really so bad that you forget what your background looks like behind your terminal?

Give Windowmaker a try, you may just like it.

Quantum Questions

As I read through books and articles about quantum physics, I have come up with a few questions over time that I still don't have a clear answer to. Maybe some other people do.

Here they are:

1. If the universe is made of symmetric particles, is it made of symmetric properties in all respects?

2. If there is a quantum universe(maybe ours), is it constant? Is it deterministic?

3. In general terms, could we ourselves be considered quantum particles to objects relatively as large as we are to quantum matter?

4. Do quantum particles always need a reason to reveal/express themselves(such as when they are measured)?

5. Strictly speaking, can information travel by other means besides waves or entanglement?

6. How does quantum matter store information, and is the type of information it can store limited?

Let me know your thoughts.

Drastic Actions

This is my first post. I have always sworn off blogs for many reasons. If you are one of those people who have yet to understand blogs, I sympathize with you. So why am I doing this? I basically want to see what the hype is about, and to see just for sure whether or not it is worth it or not. This blog will be a mixture of Linux, political things, and ideas I have for projects and research. I apologize in advance for what a bore this blog may be.