Chris Pietschmann

I’ve been questioning here and there as to what happened to Managed JScript on the Dynamic Language Runtime. The most recent preview release is really old, and it has since been taken out of any further preview releases of the DLR, where as IronRuby and IronPython continue on.

No More Managed JScript on the DLR?

For some time I never really got any good answers. Well, it’s really sad to hear that apparently Microsoft decided to drop it completely.

According the this link, a member on the DLR team has this to say:

“The DLR JScript was experimental for informing the design of the DLR (expression trees, interop, callsites, hosting, etc.). The JS we released with asp futures and the Silverlight dynamic sdk became very old and unserviceable as the DLR continued evolving for release in CLR 4.0. unfortunately, there are no plans at this time to develop and release a DLR hostable JScript.”

“Experimental for informing the design”??

I understand what this means, but since Managed JScript was used to help build the DLR from the beginning then “Why didn’t they keep it up to date?”

Plus if you go read the Initial Announcement of Managed JScript over on the JScript Blog you will see the following statement:

“We are working to make sure that Managed JScript is a first class language on top of DLR.”

What part of that post and the above statement specify that it’s only “experimental” and not to actually ever get released?

I’m really curious to find out who actually made the decision to drop it, and what the real reason is. Was it you ScottGu?

Why not Open Source it?

Well, the next logical question to ask is “Why not release what was done for Managed JScript as Open Source under a Public License?” At least this way it would allow the community to take it and run with it.

Are there Alternative Implementations?

None that I could find for .NET and/or the DLR. If you know of any, please let me know!

I did however find the Rhino project from Mozilla, but it’s for Java. According to Mozilla, “Rhino is an open-source implementation of JavaScript written entirely in Java. It is typically embedded into Java applications to provide scripting to end users.”  I guess this could be a start at building one for .NET/DLR, but…

Update: I did find the MyJScript project on CodePlex; it’s not a complete implemenation, but it does show the basics on how to create your own scripting language on the DLR. There is also an companion article to the MyJScript project: http://www.dotnetguru.org/us/dlrus/DLR2.htm

Further Info

Here’s a few links that have some small bits of info in addition to that linked above:

http://dlr.codeplex.com/Thread/View.aspx?ThreadId=58121

http://dlr.codeplex.com/Thread/View.aspx?ThreadId=41990

http://channel9.msdn.com/posts/Charles/Jimmy-Schementi-Inside-IronRuby/?CommentID=472955

http://channel9.msdn.com/shows/Going+Deep/John-Lam-and-Martin-Maly-Deep-DLR/?CommentID=472957

http://blogs.msdn.com/jscript/archive/2007/05/04/managed-jscript-announced.aspx

Conclusion

I’ve very disappointed to hear this sad news. However, I guess I could always work on building my own Managed JScript compiler/library for the DLR; if I could only find the time in between my other open source work and other paying gigs.

Until then, I guess I can only hope that Microsoft (or would it be ScottGu) decides to reconsider.

JavaScript, General javascript, dlr, .net framework