Edit: Just to clarify, I didn't intend to suggest it might be impossible to write an IDE for dynamic languages. /edit
In my specific experience I'm thinking about years of conversations/comments about JavaScript, many of them on stack, but every now and then somebody says this, that the reason JS doesn't have a decent IDE is because dynamic types make it too hard to do.
I've thought about this in terms of writing a parser for JS and I don't understand where the types have anything to do with features like auto-complete or going straight to the definitions of stuff. If anything I would imagine scope and availability through passed params in a dynamic language would be considerably easier to establish without the type-checking concern. Especially in JS where the rules are actually pretty simple in most cases.
Until I started hearing people cite dynamic types as if it were a technical blocking issue, I just assumed that in most dynamic scripting languages you can run from a console, reduced verbosity and the ease of testing in a live execution environment makes debug easier, thereby reducing demand for IDEs.
So which is it? Something about static types that makes it easier to parse code for establishing scope/availability or am I right about reduced demand?
IDEs were invented in dynamic languages. Refactoring was invented in dynamic languages. Automated Refactoring Tools were invented in dynamic languages.
Dynamic languages had graphical IDEs with builtin support for pair programming over the network when static languages didn't even have graphics. Or IDEs. Or networking support.
Smalltalk and Lisp IDEs still are ahead of what's available for Java or C#, for example. In fact, Eclipse was a Smalltalk IDE once!
The quality of an IDE is dependent on how much effort is spent making it good. The Smalltalk and Lisp communities spent decades of research, dozens of PhDs and truckloads of money building powerful IDEs. So did the Java community. (Actually, they spent truckloads of money buying Smalltalk companies …)
The JavaScript community didn't. That's the whole difference.
There are some things that need a different approach between the two. Take something like IntelliSense / Content Assist / Autocompletion, for example. Statically trying to determine what identifiers are in scope in a dynamic language is basically equivalent to solving the Halting Problem, so you can't do that. Your IDE needs to be dynamic as well, then it doesn't need to do static analysis, it can just look at the running code and see what identifiers are in scope.
Smalltalk is a dynamic language and had one of the earliest graphic based IDEs including support for refactoring. Also look at Jetbrain's RubyMine for an example of a more modern IDE for a dynamic language.
It's not impossible. It's more difficult...but then again so is writing tools for developers in general.
I am planning to implement a template engine to my erlang project, and the most important thing is the performance. Currently I have a lot of Velocity Java template, and I want to migrate templates available to erlang.
I googled it, and found things like;
http://www.ivan.fomichev.name/2008/05/erlang-template-engine-prototype.html
erlydtl
google-ctemplate
sgte
Pure erlang implementation would be the best, but c(c++) based template engine, i.e. google-ctemplate, performs better, I would use it with erlang linked in driver.
Have no experience on this matter yet, so anyone's suggestions would be super great.
thanks
My personal favourite is erlydtl. It compiles the template to an erlang module, so there's no filesystem access or parsing time consumed when you call 'render'.
I think rebar has erlydtl support these days, so getting your templates compiled is a lot less hassle than it used to be. Just name them *.dtl and they'll get built when you run rebar compile.
It should also be fairly competitive speed wise as it's in-process (skip the IPC cost of a port program), compiled (and could be compiled to native code if you wanted to), and generates iolists which are pretty efficient.
I'm looking at moving a program that currently embeds a Python interpreter to use Lua. With Python it's fairly easy to use modulefinder, compileall, and zipfile to make a nice tidy zip containing all the external libraries used.
Does Lua have the ability to bundle up its libraries like that, or is there some better best practice for distributing programs that embed Lua?
As is typical with Lua, there's no one standard and a lot of people roll their own.
There's an effort to standardize on a package-management system called Lua Rocks, but I'm not sure how much momentum is behind it or how mature it is. (In 2008 it was not quite ready for prime time, but things may have changed.)
I myself am very low tech: if I want to distribute something, I just turn my Lua sources into C files and link them in with the binary. Finding and converting all the modules could be a bit tedious for me, but quite the easiest thing for my users—they don't even need to know that Lua is involved. I've posted a copy of my lua2c script at Pastebin. I have the option of compiling but I generally don't compile because the results are not portable and because the Lua compiler is so fast anyway.
It would be nice to have something more automated. I think it would probably take several days to write and debug a good tool.
People on the Lua mailing list will surely know more.
If it is pure Lua, you might also consider using squish
It's a tool that packs all Lua source files into a single file, with options to gzip/minify it.
I want to develop an application that can retrieve information such as, DLL version, DLL build mode(debug or release), info. regarding OS, memory, processer, processes/threads, program version etc. I am developing this mainly for Windows, but it'd be good if the application supports Linux too(wherever applicable).
I am basically a java programmer, and I know C, C++ to some extent.
Which programming language should I go for, that'd make my job easy? i.e. which language has APIs to fetch these kind of information?
Well... APIs are available regardless of the language... But the easiest way to get at what you are trying to do is going to be a C or C++ app. That doesn't mean it'll be easy (getting a DLL version is easy, getting memory and processor type is easy. The other stuff is certainly possible, but you may have to roll up your sleeves and learn the win32 API).
You might want to take a look at an application that already does exactly what you are asking about (Process Explorer) before you try to develop this yourself... It's going to be a big undertaking - and the folks at Sys Internals are really, really good at this stuff, and have already done it.
You commented on Kevin Day's answer that you would prefer to use Java for this.
Java is not very well suited for this, because the information you want to get is very platform-specific, and since Java is designed to be platform-independent, there are not a lot of ways to get at this kind of information from Java.
There are some methods in classes java.lang.System and java.lang.Runtime to get information about the platform that your Java program is running on. For example, class Runtime has a method availableProcessors() that tells you how many processors are available to the Java virtual machine. Note that this is not the same as the number of processors (or cores) that exist in the computer; the documentation even says that the number may change while the program is running.
Lookup the documentation for java.lang.System and java.lang.Runtime for more information.
Most likely you're not going to get exactly the information that you need by using pure Java - C or C++ will be better suited to get this kind of platform-specific information. If you would need this information from a Java program, you could write a small DLL or shared library and use JNI to call into it from your Java program.
Since DLLs are mentioned I presume we are talking about Windows.
I would recommend using WMI queries. They look very much like SQL and give you access to many very useful classes.
e.g. all info about the OS can be found here - in W32_OperatingSystem:
http://msdn.microsoft.com/en-us/library/aa394239(VS.85).aspx
You can use WMI classes from any language including C++.
As a side note - if you start a new application from scratch consider using PowerShell - new scripting language from Microsoft.
For example, I'm running into developers and architects who are scared to death of Rails apps, but love the idea of writing new Grails apps.
From what I've seen, there is a LOT of resource overhead that goes into using the JVM to support languages such as Groovy, JRuby and Jython instead of straight Ruby or Python.
Ruby and Python can both be interpreted on just about any OS, so I don't see any "write once run anywhere" advantage... why bring the hulking JVM along with you?
Java is a much, much more mature platform, with a lot of existing class libraries that could be "dropped in" and used, than, say, Ruby or Python (or even Perl, for that matter). So for people who like using existing code, rather than writing everything themselves, Java is a huge win.
For example, recently I've been looking for something like JAXB for Python or Ruby. In the end, I ended up using JRuby just because I haven't found any mature, widely-used XML-binding libraries.
The huge advantage of writing code (in any language) for the JVM is that it's usually very easy to tap into the enormous wealth of mature Java libraries out there, if necessary.
And I don't know where you got this idea of a "hulking" JVM with a huge resource overhead. The JIT tends to produce code that is quite fast, and the core JVM is anything but huge by today's standards. It does tend to have a huge memory footprint when running, but that's because modern machines have a lot of RAM and the GC works best when it has a lot of RAM to play with. If desired, the GC can be fine-tuned to hell and back to be more conservative.
As someone else put it: "The best thing about Groovy is that I don't have to use Java. The second best thing about Groovy is that I can use Java".
An assumption that seems to be built into the question is that new projects are greenfield projects. Many organizations have made a huge investment in Java over the last decade+ and require any new project to work within the existing (internal) code ecosystem. As pointed out, there's a huge bonus in all the publicly available Java libraries (whether free/OSS or commercial), but the need to work with existing code and even as a component within an existing system is at least as important (if not more so) to large organizations.
A lot also comes down to the maturity and capability of the platform, which is to say the JVM and everything that comes with it (the entire Java ecosystem). A few examples off the top of my head:
You can plug a remote debugger into a running JVM and get all kinds of information about a running application that is simply impossible with Python, Ruby, etc. Going a step further, there's JMX, a standard way to write code so that objects can be monitored and even tweaked in a live application. Take a look at JConsole and see if you don't drool just a little (despite the ugliness of the interface).
Going even further in this direction, there's OSGi, a standard for writing highly modular code that can be deployed, started, stopped, and even upgraded in a live application. With OSGi you break a large application into many smaller "bundles" which can then be maintained (deployed, started/stopped, upgraded) separately. This is a really big deal in large applications, or any applications that need to remain running at all times.
The platform has very good support for asynchronous, reliable messaging. You get JMS as a baseline, and many excellent and powerful libraries built on it for doing complicated things with very little code (cf. Apache Camel, ServiceMix, Mule, and many others). This is another feature that's extremely valuable in larger applications or those which must run within a larger code universe.
The JVM has real (OS-level) threading, while Python et al. are very limited in this regard (notoriously so). (That being said, shared state concurrency -- threading -- is the wrong approach; cf. Erlang, Alice, Mozart/Oz, etc.)
There are numerous JVM choices beyond the standard Sun implementations, like JRockit, IBM's JVM, etc. This is a developing area with other languages -- Python has Jython, Iron Python, even PyPy and Stackless; Ruby has JRuby, Rubinius, and others -- but as good as these are they can't match the maturity found in the various JVM offerings.
All that being said, I really don't like Java the language and avoid it as much as possible. These days with all the excellent alternative languages for the JVM I don't have to. Groovy gets my vote for its accessibility and tight integration with the platform (and even the language), and because of Grails, which I sometimes like to call "Rails for grownups". I like other JVM languages better, particularly Clojure and Scala, but these aren't as accessible to the average programmer. Scala is popping up a lot lately, though, especially thanks to its high profile use at Twitter, so there's hope for interesting and truly excellent languages making it in larger environments. But that's another topic.
why bring to hulking JVM along with you?
JVM isn't bloated, nor is it slow. on the contrary, it's a lean, fast, deeply optimized VM. Unfortunately, it's optimized for static OOP languages.
Still, good compilers targeting JVM do create good performing programs. I don't know about JRuby; but Jython's goal is to be all-around faster than regular C Python, and they're getting close (it's already faster at several important use cases).
Remember that a good JIT (like those for JVM) can apply some optimizations unavailable on static C compilers, getting faster code from them isn't a pipe dream. Of course, a VM optimized for your language should be faster than a 'not-really-generic' VM like JVM; but there's the maturity issue: JVM has a lot of work done there, while JITs for Ruby and Python aren't anywhere near.
Unfortunately, there doesn't seem to be any better generic bytecode VM. Microsoft's CLI suffers from similar limitations as JVM (ironPython is much slower and heavier than JPython). The best candidate seems to be LLVM. Does anybody know why isn't there more dynamic languages over LLVM? I've seen a couple of Scheme compilers, but seem to have several problems.
Groovy is NOT an interpreted language, it is a dynamic language. The groovy compiler produces JVM bytecode that runs inside the JVM just like any other java class. In this sense, groovy is just like java, simply adding syntax to the java language that is meaningful only to developers and not to the JVM.
Developer productivity, ease and flexibility of syntax make groovy attractive to the java ecosystem - ruby or python would be as attractive if they resulted in java bytecode (see jython).
Java developers are not really scared of ruby; as a matter of fact many quickly embrace groovy or jython both close to ruby and python. What they don't care about is leaving such an amazing platform (java) for a less performant, less scalable even less used language such as ruby (for all its merits).
The big knock on RoR is that it isn't scalable and hard to deploy. By using the Java platform, you can leverage your existing infrastructure.
grails war
Produces a war file that is easily deployed on Glassfish, Jboss, etc.
Ruby and Python can both be
interpreted on just about any OS, so I
don't see any "write once run
anywhere" advantage... why bring the
hulking JVM along with you?
Mostly because you want to take advantage of the HUGE existing ecosystem of Java libraries, APIs and products, which dwarfs anything available for Ruby or Python, especially in the enterprise domain.
Also, keep in mind that JRuby and Jython are faster in a lot of benchmarks than the regular (C implementations) of the languages, especially Ruby (even Ruby 1.9).
Having multiple languages targeting the same virtual machine has a lot of benefits, such as leveraging a common infrastructure, code reuse, shared APIs, the ability to use whatever language is conceptually best for you, or for a specific problem domain, etc.
The same things happens in the .NET space, with multiple languages targeting the CLR. The Parrot (vaporware) VM project also aims to the same thing, and it's a stated goal of the LLVM project too.
The reason is Hotspot.
It is an engineering tour de force.
the other reason not many mentioned is existing infrastructure related to jvm - if you already have a server running java stuff, why not use it instead of bringing in yet another platform (like rails)?
I've encountered this and also been baffled by it, and here's my theory.
Enterprise software is full of Java programmers. Like programmers of all stripes, many Java programmers are convinced that their language is the fastest, the most flexible and the easiest to use--they're not too familiar with other languages but are convinced that those who practice them must be savages and barbarians, because any enlightened person would, of course, use Java.
These people have built vast, complicated Java infrastructures: rube-goldberg machines of frameworks and auto-generated code full of byzantine inheritance structures and very, very large XML files.
So, when someone comes along and says "Hey! Let's use a C interpreted language! It's fast and has neat libraries and is much quicker for scripting and prototyping!" The Java guy is firstly like "I have to run a make file to configure this? QUEL HORREUR!" Then the reality of having to deploy and host this on servers that are running dated OSes and dated versions of Tomcat and nothing else starts to set in.
"Hey, I know! There's a java version of this interpreted language! It may break down in the fast lane on the bridge in rush-hour, and it sometimes catches on fire, but I can get Tomcat to run it. I don't have to dirty my hands with learning non-java stuff, and I can shoehorn it into the existing infrastructure! Win!"
So, is this the "right" reason for choosing a java implementation of a scripting language? Probably not. Depends on your definition of "right". But, I suspect that it's the reason they're chosen more often than snobs like me would like to believe.