Unification is a very interesting programming tool. Originated from logical programming (its the foundation of Prolog) and used in functional programming (e.g., Haskell) it helps to compare objects for equality, identify known patterns, and reassemble results differently.

Wikipedia gives a somewhat complex definition of unification, but many people see it as an extended equivalence comparison, a pattern matching tool, and some even find parallels with XPath queries, CSS, and even jQuery, all operating on regular objects. See it for yourself.

Time and again working on big web applications we customize files based on user’s platform, and their preferences. We can send different files to legacy browsers, different CSS and JS to mobile browsers depending on their form factor, different images to accomodate bandwidth requirements, and so on.

This post was prompted by my desire to serve sprites produced by grunt-tight-sprite as WebP images to WebP-capable browsers falling back to “classic” image formats for the rest using nginx. While it is hardly a new topic, I was not satisfied with existing solutions, which all used if and rewrite, instead of simpler methods.

ClubAjax invited me to speak about technologies behind Heya , specifically about code generative solutions behind heya-pipe . Pipes are built on a firm foundation of functional programming (FP), and it allows us to use a wide range of technologies to optimize their performance including generating code on the fly (code generation AKA CG).

As soon as we are talking about CG, the first question to ask is: “How to debug such code?”. Heya provides answers for that too. But no spoilers.

After 8 years I decided to switch to Octopress . Being a server-less framework, it allows my web site to scale better, and, the most important thing for me, reduces expences on administring an active server (less active components to update). An additional bonus is that it reduces requirements for a web site host, which allows me to be more flexible when selecting a hosting company.

I spoke at ClubAjax about optimization of modern web applications. Usually I speak about theoretical matters, but this time I decided to go practical. This is a huge topic and it was blogged/debated/presented to death, including my Improving performance… . Yet I decided to add to it after realizing that many things have changed in last years, including how we build web applications. I concentrated on technical aspects completely bypassing all other areas (e.g., a psychological angle).

Once I wrote a blog post On JavaScript, EDP, and 0ms timeouts , which discussed a "smart" trend to pepper code with timeouts of … 0ms: setTimeout(f, 0). Authors of those "programming pearls" genuinely believed that this code reschedules a function call to the next available time slice after the code that set the timer was executed without introduction of a delay (after all it is 0ms!). In reality a typical delay was 10-20ms. With new generation of browsers it starts with 4ms and jumps to 1000ms for non-current/hidden tabs.

Finally: my open source JavaScript project DCL is built on ideas described in this article. Available for node.js and modern browsers, it implements OOP with mixins and AOP at "class" and object level. Read documentation and background articles on www.dcljs.org , clone its code on github.com/uhop/dcl , and follow @dcl_js .

Once again I was invited in ClubAjax to speak about JavaScript. This time I did a presentation based in part on my previous blog post OOP and JS . Slides and talk revisit OOP, mixins, AOP, chaining, and other related techniques I discussed in my blog. Of course, OOP deficiencies were discussed at length too. I suggest to look at slides and read the blog post - it will give you a better picture.

Finally: my open source JavaScript project DCL is built on ideas described in this article. Available for node.js and modern browsers, it implements OOP with mixins and AOP at "class" and object level. Read documentation and background articles on www.dcljs.org , clone its code on github.com/uhop/dcl , and follow @dcl_js .

Almost any Java programmer, who starts to study JS groking its OOP facilities and a dynamic nature of JS, thinks that they can be greatly improved and starts its own OOP library/helpers. Majority of them left forgotten when their authors learn more and more details and patterns of JS, yet some grow to fruition and being marketed. This article is dedicated to such people.

Many years ago I decided to replace plain text areas in Django’s Admin with rich text editor, so I can edit HTML on my blog using WYSIWYG. Six (yes, 6) years ago I looked around and selected TinyMCE . Over time it turned out that I was forced to upgrade TinyMCE and the link script I had because new browsers continue breaking my rich editor editing. Finally it stopped working again in all modern browsers, and I decided that enough is enough. It is time to replace it. This time I settled on Dojo’s Rich Editor hosted on Google CDN — simple, functional, less work to set up.

What happened to Dojo in 2008? This question was asked on StackOverflow. This is my personal take on the matter: on Dojo, jQuery, history, mistakes, marketing, social vs. technical, and communities .

This month I continued my presentation at ClubAJAX . Last time I did a survey of what is available in JavaScript, and concentrated on object-oriented (OOP) and aspect-oriented (AOP) techniques. This time I continued the survey, and talked about functional programming (FP), and domain-specific languages (DSL). And as promised I touched the code generation facilities too.

I suggest to read the first part before.

Enjoy!

Direct link: Exciting JavaScript - Part II .

Today at dojo.connect I did a presentation “RAD CRUD”: rapid development of form-based applications. It continues my other presentation “CRUD with Dojo” , but it is more in depth, targets Dojo developers, and contains some advanced material.

Direct link: RAD CRUD .

View more presentations from Eugene Lazutkin .

I was asked to talk about advanced JavaScript techniques at the last monthly meeting of ClubAJAX — monthly get-together of Dallas-area JavaScript programmers. Instead I ended up talking about leveraging cool JavaScript features to implement well-known programming techniques and paradigms: OOP , AOP , FP , and so on.

Unfortunately I couldn’t finish in time, so I did a tour of some language features, and talked about OOP and AOP. The rest (I plan to do FP, code generation, and DSL ) will be covered later.

Wolfram Kriesing asked :

Somehow I have the feeling that you can bend dojox’s charting module to look and feel like http://highcharts.com/ — will be for free.

Yes, it is relatively simple. To prove a point I wrote a quick-and-dirty demo available here: Tribute to Highcharts . Obviously not everything matches 100%. Go and judge for yourself.

Update: related post on dojo-dev mailing list , which explains some details of the demo.

My presentation at ClubAJAX got off to a rocky start: I was let in the building 40 minutes after I was supposed to start the presentation. Everybody waited patiently. Thank you guys! As promised I publish slides along with relevant links (I had to skip most of planned demos).

Here is my presentation on SlideShare : CRUD with Dojo . The original presentation can be seen on Google Docs: CRUD with Dojo .

Time to time I sync my blog software to the Django trunk and introduce small enhancements. Some of them visible to my readers, some of them are just for me. This time after reading Simon Willison ’s post on rev=canonical I decided to add short URLs to my blog as well. This is a convention to provide custom short URLs managing the mapping on your own web site. In my opinion the idea is very cool.

Steve Yegge is one of the bloggers I read almost religiously. His posts are full of insights on the software development topics and in general, and he is always ready with an amusing anecdote from his rich life. His last post Have you ever legalized marijuana? didn’t disappoint either. The author explains “Shit’s Easy Syndrome” (a difficult topic even for seasoned bloggers) in a gay romp that takes a reader from a light-hearted review of a book on “bugs in our mental software” to hapless VPs to many technical difficulties of legalizing a psychoactive drug extracted from the plant Cannabis sativa . But the most entertaining and educating part is the incredible story of the author’s life.

Explaining some dark corners of JavaScript, browsers, or Dojo for the 100th time I realized that I already did it on numerous occasions, and some of my answers are published on public web sites. So I decided to round up the most general ones I posted on StackOverflow and publish links to them here for a future reference.

JavaScript

This section is for language-specific topics. They can be equally applied in any environment.

As you may know today Google released Friend Connect . I decided to give it a try. It took about 20 minutes to set up my blog with 4 gadgets: Members, Sign In, Rate/Review, and Wall/Comments. It took about 30 minutes to separate the skin from all these widgets, and set up the Canvas so users can see gadgets in a separate window, if they want to.

Google Friend Connect doesn’t have any server-side components on user’s server — everything is handled by Google. All you have to do is to deploy 2 (two) static HTML files, and add various snippets that can be customized and generated on the Friend Connect’s web site. The resulting snippets are simple, and can be easily understood and restructured.

In the previous post we explored “array extras” and how they can help us to write concise yet performant and clean code. In this post we take a look at generalizing recursive algorithms with recursion combinators — high-level functions that encapsulate all boilerplate code needed to set up the recursion. These functions were added to dojox.lang.functional and will be officially released with Dojo 1.2.

In general the recursion is a form of iterative problem solving in the same category as loops. There are two major natural sources of recursive algorithms: recursive data structures (lists, trees, and so on), and recursive definitions (factorial, Fibonacci numbers, the GCD algorithm, etc.). The recursion plays a prominent role in the functional programming (FP), and one of the best articles on this topic is “Recursion Theory and Joy” by Manfred von Thun , the creator of Joy (a purely functional programming language with Forth-like syntax). Manfred’s article explains intricacies of recursion including the venerable Y combinator , recursion combinators in general, and introduces a practical set of recursion combinators, which will guide us in this post.