A Simple Code Kata

Hello CtJ nation!

Yes, it's been a long time, but we're still here at CtJ HQ, reading, if not exactly writing. Hopefully, more to come on that front in the coming weeks.

For now, this post is in support of an upcoming session at the PEI Developers Meetup. We'll be implementing a simple Code Kata and possibly extending it in interesting ways.

The Kata

The idea is a simple card game. Ignoring the rules of Rack-O, check out its deck of cards: numbers, but no suits.

The game is described as follows:

Begin with the deck of cards numbered 1 to N.

Shuffle and deal cards evenly to P players and a "kitty". That is: partition N cards (face-down) into (P + 1) sets.

Gameplay for a round:

• Show a card, face-up, from the kitty.
• Players all submit a hidden card as a bid.
• Once all bids are made, the cards are revealed.
• Highest bid wins the card from the kitty, and its value is awarded as points to the player. 

The winner is decided by most points at the end of the game.  

Notes

I like this kata for many reasons. First, it scales nicely: we could write code for a single round, and eventually ramp up to a game server with concurrent players.

Also, it combines simplicity and variation: it is easy to write an algorithm that satisfies the rules; yet a winning strategy can be dynamic and surprisingly complex. (Thanks to Alex Stangl for an email conversation on this, some years back.)

Finally, we can imagine a "robot wars" scenario where solutions compete against one another. Neat-o.

Upshot

For PEI Devs, think about this problem for the upcoming meeting.

For all, I'm looking for name suggestions (since it is not the game Rack-O). The best I have is Frak-O...

Funcito: wrap Java methods for FP libraries

On and off, I've been collaborating with my friend, Kevin Welker, on an open-source project: Funcito. This is really his baby, but it has been great fun to be involved (more to come in another post).

Executive Summary

From the FAQ, Funcito is a Java library that simplifies access to functional programming APIs by wrapping Java methods as the function-type objects defined in those libraries. It reduces boilerplate now, without waiting for changes in Java 8.

The syntax (and internals) is influenced by Mockito, the popular mocking framework. However, Funcito is not aimed at testing.

It supports specific interfaces in Google Guava, Functional Java, and Jedi-core. See the project page for details.

Example in straight Google Guava

Here is example code for using Google Guava, using a List of Song objects.

The setup is simply populating the list:

public void init() {
    // List<Song> songs is a member
    songs.add( new Song("Help!", "The Beatles", new BigDecimal(1.29) ) );
    songs.add( new Song("You Had Time", "Ani DiFranco", new BigDecimal(0.99) ) );
    songs.add( new Song("Shoot to Thrill", "AC/DC", new BigDecimal(0.89) ) );
    songs.add( new Song("Back in Black", "AC/DC", new BigDecimal(0.89) ) );
    songs.add( new Song("Indie Song", "Obscure Band", BigDecimal.ZERO ) );
    songs.add( new Song("Demo Track", "College Jam", BigDecimal.ZERO ) );
}

Here is an example test, using a predicate method on Song, isFree(), to filter for free songs:

public Collection<Song> filterFreeSongs() {
    // boilerplate alert!  
    Predicate<Song> isFreePredicate = new Predicate<Song>() {
        public boolean apply(Song s) { return s.isFree(); }
    };

    Collection<Song> freeSongs = Collections2.filter(songs, isFreePredicate);

    // size == 2 in example
    return freeSongs;
}

Note the typical pattern to build a Predicate, even though the object is simply calling a boolean method. Funcito addresses precisely this issue.

Example with Funcito

Using the same setup, here is the same test using Funcito. Note the proxy object, CALLS_TO_SONG:

// member of class
// using static import of Funcito's callsTo    
private Song CALLS_TO_SONG = callsTo(Song.class);

public Collection<Song> filterFreeSongs() {
    // using static import of Funcito's predicateFor    
    Predicate<Song> isFreePredicate = predicateFor(CALLS_TO_SONG.isFree());

    Collection<Song> freeSongs = Collections2.filter(songs, isFreePredicate);

    // size == 2
    return freeSongs;
}

Less boilerplate, with improved readability and a fluid syntax!

The Upshot

If you are using straight-up FP libraries in Java, and want to reduce some of the boilerplate, check out Funcito. It's lightweight with minimal dependencies (either CGLib or Javassist), and can help you wrap up simple Java methods.

Groovy Talk

I recently gave an "Intro to Groovy" talk for a local CIPS chapter.

It was a special evening: I returned to my alma mater, re-united with old friends, and met enthusiastic students.

I assumed the audience wasn't familiar with Java, and so the narrative was a high-level report of the blossoming ecosystem on the JVM over the past few years, with examples in Groovy. The material is available here.

My thanks to those who attended!

Strange Loop Videos

This won't be news to most readers, but if, like me, you were not able to attend Strange Loop 2011: take heart. The videos are being released online at InfoQ. Here is the schedule.

The lineup is truly outstanding. For more about the conference, check out Weiqi Gao's review.

Blogger, OpenID, and Stack Exchange

I'm a big fan of Stack Exchange and have invested a fair amount of time on various accounts on there (mostly Stack Overflow, less on English and Music).

However, I have to admit that I do not keep up with their various escapades with OpenID. I hear about it on the podcast/blog, but I haven't paid much attention.

However, every now and then, it seems as though I can't get into my accounts via my Blogger URL. Not good.

Strictly speaking, I should research OpenID, Blogger's implementation thereof, and then study the trials and tribulations of Stack Exchange. Then, I could summarize it for you, dear reader, and we could reflect, philosophically, on the sharp corner-cases of the web while enjoying a beverage in a local pub.

This isn't one of those posts. This one is simply intended as a modest link-post of gratitude (aka "this worked for me!").

The Problem

When I visited a Stack Exchange site recently, I couldn't login via my Blogger URL, and may not have even been presented with the familiar login icon that I had been using.

One Solution

Follow the steps in this post on JMPinline, including creating a Google Profile and updating with the new links.

Presumably, Stack Exchange uses OpenID 2.0 now and this will upgrade your Blogger OpenID to that version.

Either way, I was immediately able to login to Stack Exchange. My sincere thanks to the original author!

HTH

Your Blog... Sucks

Hello CodeToJoy Nation!

Yes, yes, it has been too long since the last post. The internet has weighed in, and we have noticed.

Your friend and mine, Weiqi Gao, notes that "Nobody I know posts much any more".

The inimitable Nate Neff wrote to me with a succinct critique of my writings in the last year:

Your blog... sucks.

Well. On the evidence, assuming small, frequent updates are important (which is fair): guilty as charged.

However, I don't consider this blog defunct at all; in fact, I often talk about "the glory days" from a few years back.

I've been grappling with writing an annual retrospective, now that I have been pursuing a new chapter for over a year. The trick here is that challenges and triumphs have been much more on the soft side of software: team dynamics instead of technical innovation. I wrote an article along these lines for the NFJS magazine back in April. The article drew on years of experience, but the inspiration originated in my new world.

As I write this, I realize that I'll have to shelve that post and simply post smaller chunks. Stay tuned! I'm still here.

Maritime DevCon 2011

I'm back from a jaunt to Fredericton, New Brunswick, for Maritime DevCon. Here's a post that lies between a 'random walk' and a review.

Background

From PEI originally, I've spent most of my career in St Louis/USA. I've been an active member of the user group/conference scene there. When I moved to the Maritimes in 2010, I wondered if I could find 'my people' who can/read write in the original Geek.

The upshot is: these are my people. This one-day event was a gem. The organization was first-class (good food, killer door-prizes). The topics were interesting and straddled the fence between pragmatic and esoteric-but-neat (reminiscent of Strange Loop). Most importantly: the 'spark' was there; that palpable energy that naturally spins out of conversation between interesting techies.

Venue

Maritime DevCon was held at the Wu Centre at the University of New Brunswick. About 70 people attended, notably giving up a Saturday to spend time talking tech.

Talks

Here is the schedule. I attended these talks:

OpenStack 101 (by Sandy Walsh)

I'm not especially familiar with cloud computing, or virtualization, so I was surprised to learn that Open Stack is a huge initiative among big players (e.g. Intel, Cisco, and... NASA!?). The architecture involved here is mind-blowing: will the real platform please stand-up?

Random thoughts:

• I often wonder if programming language X will be the Next Big Thing. Though it is in a different scope, virtualization is Right Now. Every time I think I have an appreciation for its influence, I see another talk where the landscape has changed ever further.
• Pythonistas unite! Though thinking at this level often reduces the programming language to an implementation detail, I was delighted to hear that the underlying system is written in Python.
  

Redis (by Peter Doan)

At other conferences, I've missed talks on Redis, the key-value store. On the way to NB, I listened to a changelog interview with the author, Salvatore Sanfilippo. Consequently, I expected a simple, near-minimalist API, and Peter confirmed that with his code examples. Works for me.

Natural Language Processing with Java (by Chris Nicholls)

Interesting piece on the state-of-the-art in NLP, especially sentiment analysis. The two main libraries are LingPipe (not free) and Apache's OpenNLP. I hadn't thought about NLP in a long time, and certainly not with respect to Twitter: (a) Twitter could be a gold-mine (b) '#' is a legit, vital punctuation mark.

Git (by Chris Dail)

This was a thoughtful, solid intro to Git. I've been away from Git for awhile, so this was useful refresher, and pulled together a couple of tectonic plates floating in my consciousness.

I especially enjoyed a section described branching in terms of highway lanes rather than trees. I appreciated anecdotes about using the Git client for Subversion as a rebel effort to 'subvert Subversion'. Note that Chris has a detailed blog post about migrating from Subversion to Git.

Node.js (by Justin Vaillcourt)

Node is another topic that I haven't seen yet. For this talk, as my friend Weiqi Gao would say: you had to be there. This was pure, unadulterated hackage, executed by a pack of young, feral dogs with unbridled enthusiasm for technology.

Justin grinned though an abbreviated talk that ranged wildly. Just when frat-house interactions with his posse threatened to steal the show, out came jaw-dropping illustrations of Node.js.

A key example used the socket.io package:

• a visitor hits a website and scrolls around
• an admin console shows a thumbnail of page the visitor is viewing
• as the visitor scrolls, navigates in his/her browser, the thumbnail scrolls in the admin console

This was done about 150-200 lines of Javascript. I don't know if this is a strong Node example. I'm still trying to wrap my mind around it.

MongoDB (by Derek Hatchard)

As with Redis and Node, I'm familiar with the buzz of MongoDB but hadn't looked into it. From the perspective of presentation techniques, this was a strong talk. A good arc from the motivation through to code examples, with images instead of bullet-lists.

Like Redis, the MongoDB API is deceptively simple. It's hard to appreciate the power. I was happy to see explanation of sharding with MongoDB, and very happy for an introductory theme on "no silver bullet", applied to relational DBs and NoSQL tools.

Suggestions

My main suggestion is that the sessions should have written evaluations. This benefits the speakers, the organizers, and ultimately the attendees. Also, there should be an overall conference evaluation.

Bottom-line

It is non-trivial to travel from PEI to Fredericton, but DevCon was worth it. The material and the energy felt like events in larger urban centers, and that's saying something.

A shout-out to Derek Hatchard, other organizers, and sponsors: thanks! I'll be back next year, as an attendee (or possibly as a speaker?): after all, these are my people.