We have a failing test from yesterday, which is a cool way to end a day for a hobby project.
[info] Moving to the left the current piece should
[info] + change the blocks in the view,
[error] x as long as it doesn't hit the wall
[error] '(0,0), (-1,17), (0,17), (1,17), (0,18)' doesn't contain in order '(0,0), (0,17), (1,17), (2,17), (1,18)' (StageSpec.scala:8)
Yesterday, we approximated the game state using String. Let's see how we can improve this.
modeling the game
On screen there should be a 10x20 grid. I only want the current piece to be rendered in different color. We'll deal with the next piece window later. The different kinds of pieces can be represented using case objects:
Every now and then I get an urge to explore a new platform, new ways of thinking, even a new programming language. The first thing I try to implement is always the same: a clone of the famous falling block game. I've implemented them in I think eight languages, Palm V that I borrowed, and on Android. Probably the first Scala program I wrote was Tetrix too. Some had network capability so two players could play against each other, and C# one had AI that kept playing on its own.
Unlike XML-based build tools sbt's build definitions are written in Scala (for both .sbt and .scala). This means that once one gets over the hurdle of learning sbt's concepts and operators, it doesn't take much for build users to start writing sbt plugins.
I've ported a few from sbt 0.7 before, but I've also been writing some original ones recently that I'd like to share.
Scala the language is one of the most elegant, expressive, consistent, and pragmatic languages. From pattern matching to the uniform access principle, it got so many things right. And Scala the ecosystem and Scala the community only makes it better.
In Scala 2.9.1, locally declared implicits are preferred over imported ones. The problem is that the spec does not cover such behavior. My original hypothesis was that either I did not understand the spec correctly, or the spec was wrong. Based on the assumptions, I set out to explore the implicits resolution precedence last week. Like MythBusters say, the best kind of result is when you get something totally unexpected. It turns out that both of the hypotheses were wrong.
My understanding of the relevant part of the spec was correct, and spec was correct as well. According to SI-5354, what's wrong was the compiler implementation:
Northeast Scala Symposium 2012 is coming up in a few months, but I want to revisit a talk from this year's nescala to wrap up 2011. One after the other, nescala had amazingly high quality of talks. You can check them all out here. With Daniel's Functional Data Structure and Jonas's Akka each having an hour-long key notes, the symposium left an impression on me that actors and FP are two major forces within Scala community. (Paul declaring that sending messages to actors is not referentially transparent was a hint too, I guess) There were also earlier signs of how the year turned out, like Mark's sbt 0.9 presentation and Nermin's Scala performance consideration. One talk that stood out in terms of immediate impact to change my code was Josh's talk: Implicits without the import tax: How to make clean APIs with implicits.
Just wanted to share a few techniques of everyday coding using some of the Scala tools.
Suppose you're developing a tool or a library, and you get a bug report. My first focus, before I start analyzing the cause, is to reproduce the issue using the same data the user is using. Once the issue is reproduced, then you can move on to simplifying the issue into a failing spec or functional test. Once the bug is fixed, you can then use the same setup to confirm the fix using the real data.