Currently I’m reading up on the following computer languages:
Python - fun, easy to learn, batteries included
Boo - fun like Python, but with macros and type declarations so that it can run fast.
Erlang - very brief code. I’m impressed by how concise the Wings3D source code is.
Typed Scheme - Scheme with type checking. (Could in theory run fast.)
I may try implementing my old “Dandy” game in these languages to see how they feel.
Ever since I’ve upgraded to Apple Macintosh OS X 10.5 Leopard, I’ve run into problems using the Darwinports “port” command to install new software.
The problem is that for some reason the version of GNU “patch” that I have installed in /usr/bin/patch is version 2.5.8, and it doesn’t operate the way that Darwin ports expects. A typical error message is:
---> Applying patches to erlang
Error: Target org.macports.patch returned: shell command " cd "/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_release_ports_lang_erlang/work/erlang-R12B-0" && patch -p0 < '/opt/local/var/macports/sources/rsync.macports.org/release/ports/lang/erlang/files/patch-toolbar.erl'" returned error 2
Command output: Get file lib/toolbar/src/toolbar.erl from Perforce with lock? [y]
Perforce client error:
Connect to server failed; check $P4PORT.
TCP connect to perforce failed.
perforce: host unknown.
patch: **** Can't get file lib/toolbar/src/toolbar.erl from Perforce
Error: Status 1 encountered during processing.
The work-around is to define the environment variable POSIXLY_CORRECT=1 , as in:
POSIXLY_CORRECT=1 sudo port install erlang
Now, I’ve done some web searching, and I haven’t seen anyone else complaining about this problem, so perhaps there’s something odd about my setup.
Yesterday I wrote a web scraper. A web scraper is a program that crawls over a set of web pages, following links and collecting data. Another name for this kind of program is a “spider”, because it “crawls” the web.
In the past I’ve written scrapers in Java and F#, with good results. But yesterday, when I wanted to write a new scraper, I though I’d try using a dynamically-typed language instead.
What’s a dynamically-typed language you ask? Well, computer languages can generally be divided into two camps, depending on whether they make you declare the type of data that can be stored in a variable or not. Declaring the type up front can make the program run faster, but it’s more work for the developer. Java and F#, the languages I previously used to write a web scraper, are statically typed languages, although F# uses type inference so you don’t actually have to declare types very often – the computer figures it out for you.
In order to scrape HTML you need three things:
Unless you’re using Mono or Microsoft’s Common Language Runtime, the language you choose will restrict the libraries that you can use.
So, the first thing I needed to do was choose a dynamic language. Since I just finished reading “Practical Common Lisp”, an excellent advanced tutorial on the Lisp language, I though I’d try using Lisp. But that didn’t work out very well at all. Lisp has neither a standard implementation nor a set of standard libraries for downloading web pages and parsing HTML. I did some Googling to try and find some combination of parts that would work for me. Unfortunately, it seemed that every web page I visited recommended a different combination of libraries, and none of the combinations I tried worked for me. In the end I just gave up in frustration.
Then, I turned to Python. I had not used Python much, but I knew it had a reputation as an easy-to-use language with a lot of easy-to-use libraries. And you know what? It really was easy! I did some web searches, copied some example code, and voila, I had a working web spider in about an hour. And the program was easy to write every step of the way. I used the standard CPython implementation for the language, Python’s built-in urllib2 library to fetch the web data, and the Beautiful Soup library for parsing the HTML.
How does the Python compare to Java and F# for web scraping?
Python Benefits:
Python non-issues for this application:
F# Benefits:
F# Non-issues:
F# Drawbacks:
Java benefits:
Java drawbacks:
Lisp drawbacks:
Looking to the future, I’d be interested in writing a web scraper in IronPython, which has good IDE support, and in C# 3.0, which has some support for type inference.
In any event, I’m left with a very favorable impression of Python, and plan to look into it some more. In the past I was put off from it because it was slow, but now I see how useful it is when speed doesn’t matter.
[Note: When I first wrote this article I was under the impression that CPython didn’t support threads. I since discovered (by reading the Python in a Nutshell book) that it does support threads. Once I knew this, I was able to easily add multi-threading to the web scraper. CPython’s threads are somewhat limited: only one thread is allowed to run Python code at a time. But that’s fine for this application, where the multiple threads spend most of their time blocked waiting for C-based network I/O ]
Curious about the internal designs of GPUs, CPUs, and game consoles? Tired of lame articles full of uninformed speculation and fanboy rants? Then check out the archives of the “Hot Chips” conference, an annual conference where computer chip designers get together to brag about their latest chips. The conference presentation slides are all online, and they’re full of good technical information on GPUs, CPUs. and even game consoles. Of course, presenters often gloss over any technical problems with their chips, so you won’t get the full picture. But these presentations offer a detailed technical look inside otherwise secret system architectures.
(For what it’s worth the web site is poorly organized, and many links are broken – you sometimes have to edit the URLs slightly to find the correct links.)
Some highlights:
Reality Co-Processor, Ken Hayes (Silicon Graphics, Inc.) - All about the Nintendo 64.
Gekko: A PowerPC compatible processor supporting high- performance 3D Graphics - Gamecube CPU
According to a presentation at the 24th Chaos Communication Congress, hackers have apparently been able to defeat the Nintendo Wii game console’s security system using tweezers to bypass the hardware memory protection.
The way it works is that the Wii runs in two modes: a GameCube emulation mode, which has access to just 1/8th of the total memory, and Wii mode, that has access to all the memory.
Hackers had already figured out how to run their own code in GameCube mode. So the trick was to run their code in GameCube mode, then use the tweezers to short out the address lines to allow the hacker’s code to access parts of rest of the memory. By shorting different address lines different portions of memory were made available. By collecting enough shards they eventually mapped all of memory.
Apparently the Wii operating system keeps its digital signature keys in this protected memory, and once the digital signatures were found it was possible to sign and run homebrew code on the Wii.
It is not clear to me whether the attack is a per-machine attack or a break-once-run-everywhere attack.
I was searching for information on LINJ, a Lisp language that compiles into human-readable Java code. Unfortunately, the LINJ web site http://www.evaluator.pt/linj.html, is currently offline.
Luckily, it turned out that the Internet Archive Wayback machine had cached both that page, and the download files that that page had pointed to. Very cool!
Similarly, I was looking for the source to the Windows CE port of Quake 3, and found that the project’s web site http://www.noctemware.com/q3ce.html had been abandoned and taken over by spammers. Luckily the Wayback machine had cached both the original web page and the downloads.
Let this be a lesson to you aspiring open source developers out there: It’s better to store small open-source projects in a large “won’t-ever-go-away” source repository like SourceForge or Google Code than to use your own vanity domain hosting. Of course, even using a large popular repository is not failure-proof. Some large code repositories from the early days of the Internet, like DEC’s ftp site, have gone away after their owning company was bought by another company. Perhaps some sort of distributed system of discoverable git repositories is the answer.
In the case of Quake 3 for Windows CE, I’ve contacted the author, Christien Rioux, and with his kind permission I’ve set up a code.google.com project so that other people can more easily find the sources (and binaries): http://code.google.com/p/q3ce .
I’ve been thinking about Lisp lately. A powerful language, with many excellent features, but not hugely successful. And I thought of one reason why:
The excellent book Guns, Germs and Steel hypothesizes that agriculture displaced hunting and gathering because people who practiced agriculture stayed in one place, and were able to have one child per year, as opposed to the hunter- gatherers, who had to wait until their children were old enough to walk before having another child. This reproductive rate difference was amplified by the ability for a given unit of land to support more farmers than hunters. As a result, agriculture displaced hunting even though individual hunters were far healthier (as seen by their skeleton height) than the farmers that displaced them.
So it is possible for a poorer technology to displace a better one, if it has compensating advantages. And I think that’s what’s hit Lisp. C and Java, which are each less powerful and more wordy than Lisp, are more successful for reasons other than power and brevity. Perhaps because both languages allow lots of reusable code to be written by ordinary programmers. Maybe Lispers are like healthy hunters, being displaced by hordes of sickly farmers.
Well, no doubt the Lispers will take some comfort in the Java and C programmers being displaced in turn by whatever language next becomes even more successful, just as hunter-gatherers may take pleasure in the trend that farmers are gradually being displaced by urban dwellers. (Come to think of it, Lispers have already seen their original competitor Fortran displaced by C/C++, and in turn much of C++ has been displaced by Java and C#.)
I think something similar is happening in productivity applications, as a generation of not-very-good-but-web-based productivity applications is displacing the Microsoft Office suite. (For example, I am typing this blog entry into a simple and ugly HTML-based web form rather than a beautiful Word document.)
This week I converted my family’s main computer from Vista to OS X. (It’s a Mac Mini).
We pretty much use it for web surfing, web email, really old DOS children’s games, and photo editing. Macs do that pretty well.
I still have a Vista machine that I use for the excellent Windows Media Center – love the record-by-keyword feature and the free programming guide.
But for day-to-day use we’re back to the Mac.
I’ve spent roughly 4 years of midnight-engineering time looking into the cool languages to see if they would make game programming easier or more fun. Haskell, Ocaml, F#, Erlang, Scheme, Lisp, D, Factor, Scala, Python, I’ve looked at them all.
F# held my attention for quite a while, but now my platform-of-choice has moved away from F#’s design center. (I’m into Linux- based mobile platforms now.) And to be honest, I’m still happier in a C-like language.
I’m depressed. Sure, I learned a lot about fancy language features, but I could have written quite a few games in plain-old-C++ (or C#, or Java or Flash or Basic) in the same time.
P.S. Someone else has done this more impressively than I have. Do a Google Groups search for Brandon van Every, who has had a five year odyssey to find the perfect non-C++ game programming language. I corresponded with him back when we were both interested in O’Caml. Since then he’s managed to annoy pretty much everyone by harping on their favorite language’s shortcomings. In the end (at least as of six months ago) he’d given up and gone back to C++. I look forward to seeing what he does next.
I’ve been poking around with Lisp and Scheme again, and am reminded of some of my favorite science fiction books (warning, plot spoilers follow):
Working with Lisp reminds me of these books. Lisp’s a seductive, ancient, powerful language that has been worked on for years by very smart, very motivated hackers. Pretty much everything one can think of to do with Lisp has been done, multiple times, by really smart people.
For example, I want to have a system where I can interactively write a game, changing code on the fly while the game is running. I want to be able to use macros and garbage collection and free serialization and inspection and all that cool stuff that Lisp provides.
And Naughty Dog had all that, in GOAL, for the PS2. Their implementation was apparently much better (more efficient, less buggy, more features) than one I could cobble together out of open-source-Lisp parts. And they had used it to successfully write two or three games. But they they walked away from it. Gave it up. Went back to C++.
They said it was because they had a lot of pressure from their parent company to make their engine more reusable. But I think it’s also because the results they were getting just weren’t that much better than the results that all the other developers, who use C++-and-some-cheap-scripting-language-like-Lua, were getting.
I think Lisp is like a powerful alien technology that may not be in your best interests to use.