I'm interested in learning about Boo's more powerful features such as syntactic macros, parser support (Ometa?), compiler pipeline, etc. My impression is that these areas have been in flux and somewhat under-documented. Are there any good resources for learning about these things other than studying the source code?
ask code gardener / boo author #rodgrigobamboo!
"boo metaprogramming facilities I - the ast".
There's Building Domain Specific Languages in Boo. I got an early early access edition and found it frustrating for the "flux" reason you mentioned; I finally gave up. Hopefully things have stabilized since then.
Feel free to ask questions on the mailing list:
http://groups-beta.google.com/group/boolang?pli=1
By far the best reference to see what Boo can do is to spend a bunch of time going through the tests. It takes a while to puzzle out what's going on, but the tests really do flex all of the muscles that are available and are quite well written.
https://github.com/bamboo/boo/blob/master/tests/testcases/macros/macro-1.boo
Also, note that boo's interpretter- booish- is really excellent and if you're not sure how a test works, you should probably spend time in booish prodding at it.
http://boo.codehaus.org/Interactive+Interpreter
I haven't looked through this site extensively, but it appears it may have the best references for Boo:
http://boo.codehaus.org/Tutorials
This section is still not well documented but if you look at https://github.com/bamboo/boo/wiki/Syntactic-Macros you can see how to make syntactic macros. Basically you have to implement Boo.Lang.Compiler.IAstMacro.
The correct section is in https://github.com/bamboo/boo/wiki/Abstract-Syntax-Tree but it largely seems incomplete.
Related
I've been playing around with "Gloss" for a day now but I feel like my possibilities are very limited.
Can you recommend a more powerful library?
If there is a simple 3D library, I'd like to use it but if it gets significantly more complex then I'm also fine with staying at 2D for the moment. I can't exactly tell you what I expect from the new library but it should be more flexible and provide more (advanced) features.
PS: I'm on Windows 7 64bit if that matters
I think the question may be a little vague and "more powerful" is certainly subjective. But since you mentioned that you were on Windows 7-x64 then I can only guess to point you towards HGamer3D as a possible solution. I've heard some good things about it, but I've never used it myself. In any case there looks to be plenty to chew on there.
OpenGL.
An introductory tutorial, by Mikael Vejdemo Johansson,
loosely based on the tutorial by Sven Eric Panitz.
The title may seem slightly self-contradictory, and I accept that you can't really learn a language quickly. However, an experienced programmer that already has knowledge of a few languagues and different styles (functional, OO, imperative etc.) often wants to get started quickly. I've seen a few websites doing effective "translations" in the form of "just show me syntax equivalence". I can't remember the sites now, but for related languages (e.g. Perl/PHP) it's quite common.
Is there a better resource that covers more languages? Is there a resource that covers idioms as well as syntax? I think this would be incredibly useful for doing small amounts of work on existing code bases where you are not familiar with the language. Looking at the existing code, as we know, is not always a good indicator of quality. Likewise, for "learn by doing" weekend project I always have the urge to write reasonably idiomatic, clean code from the start. Such a resource could also link to known good example projects of varying sizes for those that prefer to learn by reading. Reading a well-written medium sized code base can also be much more practical when access to development environments might be limited.
I think it's possible to find tutorials and summaries for individual languages that provide some of this functionality in disparate web locations but I'm hoping there is a good, centralised, comparative place that the busy programmer can turn to.
You generally have two main things to overcome:
Syntax
Reference
Syntax you can pick up fairly quickly with a language tutorial and a stack of samplecode.
Reference (library/API calls) you need to find a proper guide to; perhaps the language reference, or perhaps google...
With those two in place, following a walkthrough (to get you used to using the development environment) will have you pretty much ready - you'll be able to look up what you want to say (reference), and know how to say it (syntax).
This, of course, applies principally to procedural/oop languages; languages that require a paradigm switch (ML/Haskell) you should go to lectures for ;)
(and for the weirder moments, there's SO!)
In the past my favour was "learning by doing". So e.g. I know a little bit of C++ and a lot of C#.Net but I must write a FTP Tool in Python.
So I sit for an hour and so the syntax differences by a tutorial, than I develop the form itself and look at the generated code. Then I search a open source Python FTP Client and get pieces of code (Not copy and paste, write it self to see, feel and remember the code!)
After a few hours I get it.
So: The mix is the best. A book, a piece of good code, the willing to learn and a free night with much coffee.
At the risk of sounding cheesy, I would start with the language's website tutorial and/or FAQ, followed by asking more specific questions here. SO is my centralized location for programming knowledge.
I remember when I learned Perl. I was asked to modify some Perl code at work and I'd never seen the language before. I had experience with several other languages, however, so it wasn't hard to figure out the syntax with the online Perl docs in one window and the code in another, side-by-side. I don't know that solely reading existing code is necessarily the best way to learn. In my case, I didn't know Perl but I could tell that the person who originally wrote the code didn't know Perl either. I'm not sure I could've distinguished between good Perl and really confusing Perl. It would've been nice to be able to ask questions here at the time.
Language isn't important. What is important is learning your ways around designing algorithms and the proper application of design patterns. Focus on the technique, not the language that implements a certain technique. Once you understand the proper development techniques, any programming language will just become real easy, no matter how obscure they are...
When you put a focus on a language, you're restricting your own knowledge.
http://devcheatsheet.com/ seems to be a step in the right direction: it aggregates cheat sheets/quick references and they are (somewhat) manually reviewed. It's also wide-ranging. It still comes up short a bit in terms of "idiomatic" quick reference: for example, the page on Ruby doesn't mention yield.
Rosetta Code appears to be an excellent resource that includes hints on coding idiomatically and moves from simple (like for-loops) to things like drawing. I haven't checked out how comprehensive it is, but there are a large number of languages and tasks listed. The drawbacks re: original question are:
Some of the linking is not accurate
(navigating Python->ForLoop will
take you to the top of the ForLoop
page, not the Python section). It's a
wiki, this can be improved.
Ideally you could "slice" the wiki
however you chose to see e.g. the top
20 tasks for two languages
side-by-side.
http://hyperpolyglot.org/ seems to be an almost perfect match for what I was looking for. The quality is not always there, or idiom can be lacking, but it has the same intention and is pretty comprehensive.
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Have you ever tried learning a language while on a project? I have, and from my personal experience I can say that it takes courage, effort, time, thinking, lots of caffeine and no sleep. Sometimes this has to be done without choice, other times you choose to do it; if you are working on a personal project for example.
What I normally do in this kind of situation, and I believe everyone does, is "build" on top of my current knowledge of languages, structures, syntax and logic. What I find difficult to cope with, is the difference of integrity in some cases. Some languages offer a good background for future learning and "language study", they pose as a good source of information or a frame of reference and can give a "firm" grasp of what's to come. Other languages form or introduce a new way of thinking and are harder to get used to.
Sometimes you unintentionally think in a specific language and when introduced to a new way of thinking, a new language, can cause confusion or make you get lost between the "borders" of your new and your current knowledge of languages.
What can be a good solution in this case? What should be used to broaden the knowledge of the new language, a new way of thinking, and maintain or incorporate the current knowledge of other languages inside the "borders" of the new language?
I find I need to do a project to properly learn a language, but those can be personal projects. When I learned Python on the job, I first expected (and found) a significant slowdown in my productivity for a while. I read the standard tutorials, coding standards and I lurked on the Python list for a while, which gave me a much better idea of the best practices of the language.
Doing things like coding dojos and stuff when learning a language can help you get a feel for things. I just recently changed jobs and went back to Java, and I spent some time working on toy programs just to get back in the feel for things (I'm also reading Effective Java, 2nd edition as my previous major experience had been with Java 1.4).
I think, in some respects no matter what the impetus for learning the language, you have to start by imitating good patterns in the new language. Whether that means finding a good book, with excellent code examples, good on-line tutorials, or following the lead of a more experienced developer, you have to absorb what it means to write good code in a particular language first. Once you have developed a level of comfort, you can start branching out and and experimenting with alternatives to the patterns that you've learned, looking for ways to apply things you've learned from other languages, but keeping within the "rules" of the language. Eventually, you'll get to the point where you know you can 'break the rules" that you learned earlier because you have enough experience to know when they do/don't apply.
My personal preference, even when forced to learn a new language, is to start with some throw away code. Even starting from good tutorials, you'll undoubtedly write code that later you will look back on and not understand how stupid you could have been. I prefer, if possible, to write as my first foray into a language code that will be thrown away and not come back to haunt me later. The alternative is to spend a lot of time refactoring as you learn more and more. Eventually, you'll end up doing this, too.
I would like to mention ALT.NET here
Self-organizing, ad-hoc community of developers bound by a desire to improve ourselves, challenge assumptions, and help each other pursue excellence in the practice of software development.
So in the spirit of ALT.NET, it is challenging but useful to reach out of your comfort zone to learn new languages. Some things that really helped me are as follows:
Understand the history behind a language or script. Knowing evolution helps a lot.
Pick the right book. Research StackOverflow and Amazon.com to find the right book to help you ease the growing pains.
OOP is fairly common in most of the mature languages, so you can skip many of the chapters related to OOP in many books. Syntax learning will be a gradual process. I commonly bookmark some quick handy guides for that.
Read as many community forums as possible to understand the common pitfalls of the new language.
Attend some local meetups to interact with the community and share your pains.
Take one pitch at a time by building small not so complicated applications and thereby gaining momentum.
Make sure you create a reference frame for what you need to learn. Things like how security, logging, multithreading are handled.
Be Open minded, you can be critical, but if you hate something then do not learn that language.
Finally, I think it is worthwhile to learn one strong languages like C# or Java, one functional language and one scripting language like ruby or python.
These things helped me tremendously and I think will help all software engineers and architects to really gear for any development environment.
I learned PHP after I was hired to be the project lead on the Zend Framework project.
It helped that I had 20 years of professional programming background, and good knowledge of C, Java, Perl, JavaScript, SQL, etc. I've also gravitated towards dynamic scripting languages for most of my career. I've written applications in awk, frameworks in shell, macro packages in troff, I even wrote a forum using only sed.
Things to help learn a language on the job:
Reading code and documentation.
Listening to mailing lists and blogs of the community.
Talking to experts in the language, fortunately several of whom were my immediate teammates.
Writing practice code, and asked for code reviews and coaching.(Zend_Console_Getopt was my first significant PHP contribution).
Learning the tools that go along with the language. PHPUnit, Xdebug, phpDoc, phing, etc.
Of course I did apply what I knew from other programming languages. Many computer science concepts are language-universal. The differences of a given language are often simply idiomatic, a way of stating something that can be done another way in another language. This is especially true for languages like Perl or PHP, which both borrow a lot of idioms from earlier languages.
It also helped that I took courses in Compiler Design in college. Having a good foundation in how languages are constructed makes it easier to pick up new languages. At some level, they're all just ways of abstracting runtime stacks and object references.
If you're a junior member of the team and don't know the language, this is not necessarily an issue at all. As long as there is some code review and supervision, you can be a productive.
Language syntax is one issue, but architectural differences are a more important concern. Many languages are also development platforms, and if you don't have experience with the platform, you don't know how to create a viable solution architecture. So if you're the project lead or working solo, you'd better have some experience on the platform before you do your design work.
For example, I would say an experienced C# coder with no VB experience would probably survive a VB.NET project just fine. In fact, it would be more difficult for a developer who only had experience in C#/ASP.NET to complete a C# WPF project than a VB ASP.NET project. An experienced PHP developer might hesitate a bit on a ColdFusion project, but they probably won't make any serious blunders because they are familiar with a script based web development architecture.
Many concepts, such as object modelling and database query strategies, translate just fine between languages. But there is always a learning curve for a new platform, and sometimes it can be quite nasty. The worst case is that the project must be thrown out because the architure is too wrong to refactor.
I like to learn a new language while working on a project, because a real project will usually force me to learn aspects of the language that I might otherwise skip. One of the first things I like to to is read code in that language, and jump in. I find resources (such as books and various internet sites) to help as I go along.
Then, after I've been working on it for a while, I like to read (or re-read) books or other resources on the language. By this time I have some knowledge, so this will help solidify some things and also point out areas where I am flat-out wrong in my understanding. For instance, I can see that I was making incorrect assumptions about similarities between languages.
This also applies to tools -- after using a tool for a while and learning the basics, reading (or skimming) the documentation can teach me a lot.
In my opinion, you should try to avoid that. I know, most of the times you can't but in any case try not to mix the new language with the old one, and never add to the mixture old habits, practices and patterns.
Always try to find resources that will help you get through the new language in the way the language works, not in the way other languages do; that will never have a happy ending, and if it does it will be very hard to modify it to the right way.
Cheers.
Yes I have.
I mean, is there another way? The only language I ever learned that was not on a project was ABC basic, which was what you used on my first computer.
I would recommend if you start with a certain language, stick with it. I only say that because many times in the past I tried more and more different ones, and the one I started out with was the best :D
Everytime I have/want to learn a new language, I force myself to find something to code.
But to be sure I did it well, I always want to be able to check my code and what it ouputs.
To do so, I just try to do the same kind of stuff with languages I know and to compare the outputs. For that, I created a little project (hosted on Github) with an exercise sheet and the correction for every language I learnt. It's a good way to learn in my opinion because it gives you a real little project.
I need do write an expert systems that should aid user in picking up best mobile phone operator. It should be very simple and not based on languages/libaries such as CLISP or JESS. So I need to write it all from the ground up.
Do you know some books or online tutorials that explains how this can be done?
What I really need to get to know is how to represent knowledge and facts.
Any help would be much appreciated.
If you get any of the good texts on AI, there will be a section on expert systems; you can, if forced, work it out from there and implement your own.
The basic idea is really fairly simple: you have a collection of rules in "if-then" form that represent inferences, or4 implications. Like, for example:
IF blood temperature > 41°C
THEN patient.has-fever := TRUE
IF patient has wet-sounding breathing
THEN patient.has-pneumonia
IF patient.has-fever AND patient.has-pneumonia
THEN CONCLUDE bacterial pneumonia. ACTION prescribe Augmentin
In other words, you have a bunch of rules, and you evaluate the rules until you get to a conclusion. There's a lot more to is (forward or backward chaing and that kind of thing) which you can read about in thed pretty decent Wikipedia article.
I'm puzzled why you can't use an existing rule engine though -- there are a number of them, for most languages, usually under pretty liberal licenses. That's really an easier route unless this is a homework problem or something.
Prolog is well suited to writing rule-based systems (a pretty standard approach to expert systems development). P# compiles to C#, which may meet your needs - and it's free.
More information on P#.
The basis rationale, and mathematical proof, for the PROLOG language, should help you understand most of the concepts you will need to address, if not provide the final language you need to use to implement it.
I couldn't find a link to the original implementation, but it would not help you much anyway. Alain Colmerauer's early work on logic programming should be helpfull.
[EDIT] Sorry, duplicate...
I would vote for some implementation of Prolog or CLIPS, depending if backward or forward chaining logic best suits the problem. Instead of re-implementing either of these, spend the time working out how to integrate them with your environment.
Jess is a good choice but you should read the book "Jess in action" as a first step.
Hear lately I've been listening to Jeff Atwood and Joel Spolsky's radio show and they have been talking about dogfooding (the process of reusing your own code, see Jeff Atwood's blog post). So my question is should programmers use decompilers to see how that programmers code is implemented and works, to make sure it won't break your code. Or should you just trust that programmers code and adapt to it because using decompilers go against everything we as programmers have ever learn about hiding data (well OO programmers at least)?
Note: I wasn't sure which tags this would go under so feel free to retag it.
Edit: Just to clarify I was asking about decompilers as a last resort, say you can't get the source code for some reason. Sorry, I should have supplied this in the original question.
Yes, It can be useful to use the output of a decompiler, but not for what you suggest. The output of a compiler doesn't ever look much like what a human would write (except when it does.) It can't tell you why the code does what it does, or what a particular variable should mean. It's unlikely to be worth the trouble to do this unless you already have the source.
If you do have the source, then there are lots of good reasons to use a decompiler in your development process.
Most often, the reasons for using the output of a decompiler is to better optimize code. Sometimes, with high optimization settings, a compiler will just get it wrong. This can be almost impossible to sort out in some cases without comparing the output of the compiler at different levels of optimization.
Other times, when trying to squeeze the most performance out of a very hot code path, a developer can try arranging their code in a few different ways and compare the compiled results. As a last resort, this may be the simplest way to start when implementing a code block in assembly language, by duplicating the compiler's output.
Dogfooding is the process of using the code that you write, not necessarily re-using code.
However, code re-use typically means you have the source, hence 'code-reuse' otherwise its just using a library supplied by someone else.
Decompiling is hard to get right, and the output is typically very hard to follow.
You should use a decompiler if it is the tool that's required to get the job done. However, I don't think it's the proper use of a decompiler to get an idea of how well the code which is being decompiled was written. Depending on the language you use, the decompiled code can be very different from the code which was actually written. If you want to see some real code, look at open source code. If you want to see the code of some particular product, it's probably better to try to get access to the actual code through some legal means.
I'm not sure what exactly it is you are asking, what you expect "decompilers" to show you, or what this has to do with Atwood and Spolsky, or what the question is exactly. If you're programming to public interfaces then why would you need to see the original source of the the third party code to see if it will "break" your code? You could more effectively build tests to in order to determine this. As well, what the "decompiler" will tell you largely depends on the language/platform the software was written in, whether it is Java, .NET, C and so forth. It's not the same as having the original source to read, even in the case of .NET assemblies. Anyway, if you are worried about third party code not working for you then you should really be doing typical kinds of unit tests against the code rather than trying to "decompile" it. As far as whether you "should," if you mean whether you "should" in some other way other than what would be the best use of your time then I'm not sure what you mean.
Should Programmers Use Decompilers?
Use the right tool for the right job. Decompilers don't often produce results that are easy to understand, but sometimes they are what's needed.
should programmers use decompilers to
see how that programmers code is
implemented and works, to make sure it
won't break your code.
No, not unless you find a problem and need support. In general you don't use it if you don't trust it, and if you have to use it you even when you don't trust it you develop tests to prove the functionality and verify that later upgrades still work as expected.
Don't use functionality you don't test, unless you have very good support or a relationship of trust.
-Adam
Or should you just trust that programmers code and adapt to it because using decompilers go against everything we as programmers have ever learn about hiding data (well OO programmers at least)?
This is not true at all. You would use a decompiler not because you want to get around any sort of abstraction, encapsulation, or defeat OO principles, but because you want to understand why the code is behaving the way it is better.
Sometimes you need to use a decompiler (or in the Java world, a bytecode viewer) when you are troubleshooting an annoying bug with a 3rd party library where an exception is thrown with no useful error message, no logging, etc.
Use of a decompiler has nothing to do with OO principles.
The short answer to this... Program to a public and documented specification, not to an implementation. Relying on implementation specifics and side-effects will burn you.
Decompilation is not a tool to help you program correctly, though it might, in a pinch, assist you in understanding a problem with someone else's code for which you don't have source.
Also, beware of the possible legal risk of decompiling; many software companies have no-decompile clauses which could expose you and your employer to legal consequences.