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  A Month With Scala


Although I’ve played around with Scala for the few months, these efforts largely involved simple scripts and casual reading. It wasn’t until last month that the opportunity to use Scala in a large scale project finally arose and I dove right in. The project was a typical REST based web service built on top of Amazon’s Elastic Beanstalk, SimpleDB, S3 and Redis*. First off let’s talk about why I chose Scala in the first place. After spending a good deal of my last year entrenched in...

   Scala,Functional,OOP,Java,Iteration     2011-12-10 06:03:23


  Java Sequential IO Performance


Many applications record a series of events to file-based storage for later use.  This can be anything from logging and auditing, through to keeping a transaction redo log in an event sourced design or its close relative CQRS.  Java has a number of means by which a file can be sequentially written to, or read back again.  This article explores some of these mechanisms to understand their performance characteristics.  For the scope of this article I will be using pre-a...

   Java,IO,Sequential,Blocking     2012-02-23 07:09:10


  A boolean value interview question


Someone asked a question on StackOverflow, he was asked an interview question. The question is : Given 3 boolean variables a, b, c, return true if at least 2 out of the 3 are true. He gave the solution as follows :boolean atLeastTwo(boolean a, boolean b, boolean c) {    if ((a && b) || (b && c) || (a && c)) {        return true;    } else {        ret...

   bool,return,expression,conditional     2012-04-30 08:49:32


  Haskell’s effect on my C++: exploit the type system


Like most programmers, I was attracted to Scheme by the promise that it would make me a better programmer. I came to appreciate the functional style, but swapped to Haskell, a more developed language with a rapidly developing standard library. Unfortunately, for me, Haskell can’t yet replace C++ on a day to day basis, so I reluctantly spend my days tapping away at C++. So, were the promises true? has functional programming made me a better programmer? Better is a tough question, I ha...

   Haskell,C++,Type system,Comparison     2012-02-06 07:44:35


  Understanding lvalues and rvalues in C and C++


The terms lvalue and rvalue are not something one runs into often in C/C++ programming, but when one does, it’s usually not immediately clear what they mean. The most common place to run into these terms are in compiler error & warning messages. For example, compiling the following with gcc: int foo() {return 2;} int main() { foo() = 2; return 0; } You get: test.c: In function 'main': test.c:8:5: error: lvalue required as left operand of assignment True, this code is so...

   lvalue,rvalue,C++,locator value,elaboration     2011-12-15 07:51:38


  8 very useful and free web security testing tools


With more pervasive of web applications, web security threats are becoming increasingly prominent. Hackers gain web server control by exploiting web server vulnerabilities and SQL injection vulnerabilities, then they may tamper with web content, or steal important internal data, the more serious is to inject malicious code into web pages to affect visitors of websites. Attention is gradually warming up to Web Application Security. Here we recommend eight very useful and free web security testing...

   Website, security,Web security,Attack     2012-07-22 10:59:09


  Why are column oriented databases so much faster than row oriented databases?


I have been playing around with Hybrid Word Aligned Bitmaps for a few weeks now, and they turn out to be a rather remarkable data structure.  I believe that they are utilized extensively in modern column oriented databases such as Vertica and MonetDB. Essentially HWABs are a data structure that allows you to represent a sparse bitmap (series of 0's and 1's) really efficiently in memory.  The key trick here is the use of run length encoding to compress the bitmap into fe...

   Database,Column oriented,Speed analysis,Vertica     2012-01-29 04:27:05


  A list of different CAPTCHA designs


Here is a list of website CAPTCHA designs which demonstrate all kinds of weird verification methods. By looking at these designs, as a website designer, you should distinguish which design is accessible and which is not.Is this human readable?What characters are in the picture?One moreWe will be crazy if we see theseOMG,What's the answer?IQ Test?Are you a normal person?You know how blind people read?ASCII PictureAre you an adult?3D verification codereCaptchaIt increase a new feature recently. It...

   CAPTCHA,Website design     2012-07-19 11:51:06


  Tom Uglow from Google : 5 steps to innovation


Google has been known for its innovation In Google there is a "welfare": each employee can spare 20% of his/her time to do what he/she likes to do so that any idea has a chance to be turned into reality. Perhaps this freedom makes Google capable of introducing new products and new ideas continuously. Google China held a small discussion session in its office in Tsinghua Science Park recently, Google Creative Director Tom Uglow shared some experience and cases of Google in production and innovat...

   Innovation,Technology,Google     2012-10-10 20:00:47


  Functional Programming Is Hard, That's Why It's Good


Odds are, you don’t use a functional programming language every day. You probably aren’t getting paid to write code in Scala, Haskell, Erlang, F#, or a Lisp Dialect. The vast majority of people in the industry use OO languages like Python, Ruby, Java or C#–and they’re happy with them. Sure, they might occasionally use a “functional feature” like “blocks” now and then, but they aren’t writing functional code.And yet, for years we’ve been told that functional languages are awes...

   Functional Programming,Hard,Difficult,Reason to learn,Good     2011-10-18 02:55:38