One use of the lower-case Greek letter λ is a branch of mathematical logic called Lambda Calculus. It’s a formal system designed to research function definition, function application and recursion. Throughout the years, λ has been seen on many logos related with the functional programming. For example, the MIT Scheme’s logo represents a recursive shield with lambda:

We can see lambda on the functional programming language Haskell’s logo. Apart from lambda, we can see five other mathematical symbols, representing the Haskell’s functionality. These are their respective meanings:

-The right arrow (→): Transformation
-The universal quantification (∀): For all
-The double angle (≫): Free from disorder
-The double right arrow (⇒): Generality
-The double colon (::): Exactitude

A scheme-to-C compiler called Chicken has a logo that represents a lambda inside a hen silhouette.

CL-HTTP (Common Lisp Hypermedia Server) has a lambda symbol on its logo too.

More information | Xahlee

The first century starts at 0001-01-01 00:00:00 AD, although they did not know it at the time. This definition applies to all Gregorian calendar countries. There is no century number 0, you go from -1 to 1. If you disagree with this, please write your complaint to: Pope, Cathedral Saint-Peter of Roma, Vatican.

Seen on PostgreSQL Documentation

Many people speak about the future of web applications, but I would like to stop and comment on the present. I have been observing a curious phenomenon throughout the recent years. I have seen a backwards movement as far as the way of the social communications on the Internet are concerned. For example, I can spot similarities between Twitter and the IRC, which is still in use, but not like few years ago. The first difference that I have noticed is the transmission time. The communication by IRC is synchronous, whilst the communication on Twitter is unsynchronous.

An unsynchronous communication has some advantages. The main advantage is probably the null intrusivity. An unsynchronous method is not intrusive. We can find an analogous example on the use of phone or email. When someone phones you, you have to stop what you are doing in order to answer the call. On the other hand, if someone sends you an email you can read it whenever you like. Obviously the priority plays an important role, for example if you have something urgent to say, an unsynchronous method is not the most appropriate way.

Another advantage of an unsynchronous method is the possibility of reading (or listening, or watching) a document wherever and whenever you like. It is not possible to do this using a synchronous method.

In my opinion, this regressive trend is an intelligent movement.

Thierry Henry’s amazing goal against Celtic Glasgow.

I was thinking of buying the new Canon EOS 450D (released on 24th January), but taking a look at the improvements from the Canon EOS 400D I have reached the conclusion that it doesn’t worth to pay the price difference. I bought yesterday the camera with the standard kit lens (EFS 18-55 mm). Now I’m going to upgrade my forgotten Flickr account and start uploading new pictures!

Do I love you because you’re beautiful or are you beautiful because I love you?

Since I started to build YouAre.com I knew that the scalability was an important matter to solve. Sometimes the scalability is more important for your pocket and for the success of your startup than originally thought. According to Google, a slow performance could cost you 20% of your revenue. If you are starting a new company, you ought to know that any savings in servers can accelerate the growth of your company. These costs include hardware, software, human resources and time (for many people the most appreciated resource). Apart from the monetary costs, it’s proved that half a second delay in page load time can kill a user’s satisfaction.

The scalability is a relative problem which depends on many things: the technology used, the fault tolerance and the availability of programming staff. Many people think that scalability=performance, and they are wrong as there are more aspects to be considered. For me, the scalability is to maintain the balance between the resources and the number of users, when the size of the problem increases. The size of the problem is the growth of the number of users and the resources. A graphic which represents a good scalability could be the following:

We can appreciate how well the growth of users (n) have been solved. The amount of required resources grows logarithmically.

Some good points for scalability that should be considered:

• Good database design: Normalize the database, select a suitable DBMS, consider the users’ necessities, …
• Search engines: Use a search engine for your application. Lucene is a very high-performance text search engine library. You can also consider Nutch or Solr, both based in Lucene but oriented to web applications. If you are finding some engine more basic take a look at Sphinx.
• The Keepalive problem: Enabling Keepalive for images and external files (such as CSS) is very good for clients, but bad for servers. Keeping Keepalive off we reduce a lot of the memory of the server. A good solution is to have separate images in a different server, getting the added benefit of higher browser concurrency with multiple hostnames (it will let you to load images in parallel). In YouAre, we are using Amazon Simple Storage Service to store our images.
• Cache: Cache as much of your dynamic content as possible Memcache could be a great option.
• Take care of your code: Take care of your code and it will take care of you
• Use GNU/Linux: GNU/Linux uses spare memory to cache files on disk. This means much faster I/O.

More information | Rico Mariani
More information | Shiflett
More information | No VC required

One reason I lost interest in Facebook was having hundreds of Facebook application invitations on my board. Although I must admit that at first I received invitations for interesting applications, but now it just pisses me off. Eventually my homepage was being flooded of useless, boring and repeated applications. I sincerely prefered Facebook when these types of applications were not present. Even though it was a great idea, but now Facebook probably has an interface problem that they don’t know how to solve. Today surfing the web, I have found a solution - a simple ignore all bookmark for Facebook.

Really it’s just a simple Javascript code, and when running it, it selects the ignore options on every request, apart from friend requests, group invites and event notifications. You can access this at http://www.ignoreall.com/.

For the first time since 1885, Britan is richer than the USA (by per capita gross domestic product). Dividing the GDP of the UK we obtains $46,088 this year, compared with $45,598 in the USA. We are to thank the pound’s strength against the dollar for about 75% of Britain’s advances.

Source | BusinessWeek