Quicksort in Haskell

Here is my attempt at quicksort in Haskell

quicksort :: (Ord a) => [a] -> [a]
quicksort [] = []
quicksort (x:xs) =  smaller ++ [x] ++ bigger
                   where smaller = quicksort [y| y <- xs , y < x]
                         bigger = quicksort [y | y <- xs, y >= x]
      

So how does this work?

• [a] ->[a] means that quicksort takes a list as input and returns a list as output


• (Ord a) means that a belongs to a type class Ord (i.e. a is an ordered type)


• The first expression means that quicksort returns an empty list for an input empty list


• The second expression works as follows. The input list is broken into its head and tail (x, xs). We use x as the pivot element. all elements smaller than x in xs are identified and sorted using quicksort itself (recursively). All elements greater than or equal to x are sorted by quicksort itself (recursively). The final result is smaller + [x] + bigger.

So here are some examples:

*Main> quicksort [2, 1, 3]
[1,2,3]
*Main> quicksort "i don't believe you"
"   'bdeeeiilnootuvy"
*Main> quicksort "i love you"
"  eiloouvy"
*Main> quicksort [50, 40, 30 , 10, 20, 30, 40, 50, 20]
[10,20,20,30,30,40,40,50,50]
*Main>

testing code prettifier

Just learnt about how to prettify code inside Blogger.
So trying it out now.

print "Hello World"
for i in range(10):
    print i,
print

Well this works nicely.

For more information about how to set it up, please follow it at:

http://lukabloga.blogspot.com/2008/10/to-test-new-highlighting.html

user interfaces and criticism

Be warned, this is not serious stuff !!

I happen to do user interface development most of the time. It so happens that I am never able to do something which satisfies everybody. At best I am able to do an OK job. I did get to learn some interesting things over the years.
No matter how much effort one puts in user interface development, its never enough.
Its much much easier to find out issues in user interfaces than to implement solutions which take care of them properly. So just relax.
Its much more comfortable to be in the role of a critic than in the role of implementer. So try hard to get into such a role.
If you don't like the criticism you get, just sit back and relax. Don't reply back. Just ignore it and chill.
You will not like the user interface you have done if you look back at it after a few weeks or few months time. Don't try to improve it!! Its a never ending vicious circle.

Mobicules

My long-time friends Niraj and Munish have started up a new company Mobicules. The company works in the areas of Web 2.0, social networking applications and related areas. They have been in operation for about a year now and have been doing well.
Both of them worked for Mentor (EDA) for about 5 years.
The company website is http://www.mobicules.com/.

Zope 3 Views as multi-adapters

This diagram shows how Zope Views are implemented as multi-adapters. Student is a content class which implements IStudent interface. HTTPRequest objects are created when an HTTP request (either through Web browsers, or through XML-RPC calls) is made. StudentView is an adapter which adapts a Student object along with an HTTPRequest object and implements IBrowserView interface.

The diagram is not accurate reflection of design of browser views in Zope. It is just for demonstration of the idea of multi-adapters.