Sunday, September 7, 2008

Dynamic Language Runtime (DLR), IronRuby and Advantages

What's being popular out there right now is something called IronRuby, which is an implementation of the Ruby language in .Net, which is built indirectly on top of the CLR.
So let’s talk a little about how IronRuby fits into the .Net world, something that you should know at this point is that Microsoft is building a common platform for dynamic languages called the Dynamic Language Runtime or DLR for the short, which runs as a service on top of the CLR.

DLR provides common functionalities like MSIL generation, GC, so that dynamic language implementers can focus on the implementing there dynamic language on top of this without worrying about the “gooing” part to the CLR.
All that the language implementer needs to do at runtime is to parse the language, tokenize it and create a tree structure containing the expressions and statements and pass it on to the DLR.
At the next step the DLR is going to generate MSIL from these trees, and the MSIL would execute under the CLR. Some pretty interesting things to note here is that when the DLR does not know how an operation should be actually executed, it looks at the currently executing dynamic language and ask it how the operation should be done, then the language responds with another tree on how the operation should be done, if the language does not know how the operation should be executed than the DLR takes a default action into evaluating the expression.

Something interesting to note here is that, these trees that the DLR gets back from asking questions on how to do certain thing in a language is actually cached, so that the next time the DLR encounters something like that, it looks at the cache for an answer, and does not go through asking the language for help.

The DLR is still being built and up to now developers involved in the DLR , says there are lot more work to be done.
The whole point of the DLR and the language actually complies into MSIL and gets executed under the CLR is interoperability between these dynamic languages built on top of the DLR and other .Net languages. This would actually mean that you can consume a library that was written on one of these languages inside C# or vise versa, i.e. consuming a C# library from these dynamic languages.

This brings us to the advantages of this hectic effort, something that most developers face is covering unit testing of there respective module, one the problems that they face is the time limit when writing these in something like C# or Java.
Now, with dynamic languages being able to interop, you can write your unit testing in a language like IronRuby and consume your .Net APIs. This is much easier cos' writing your test cases in a dynamic language is must faster, and increase your productivity.

Another area where this can help is in the area of domain specific languages (DSL), where your domain specific grammar can be written in a language like IronRuby or IronPython and where your actual code generation can happen in a statically type language like C#.
This effort is also worth while in places where we use XMl as “processing” language, like in build scripts, where your build "logic" can be written in a language like IronRuby, after all writing logic in a programming language is much easier then writing in XML, I never liked XML for these purposes anyway..

There are some dynamic languages that are being implemented now, like IronRuby and IronPython, and there initial implementation can be downloaded and played around with. I choose IronRuby as the language and trying it out a little bit now a days, you can try it out too, but before that, try learning the real power in dynamic languages and try playing around with Ruby before you go ahead with IronRuby.

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