Microsoft has released the 4.0 version of the .Net Framework and Visual Studio 2010. The release includes several framework enhancements. The Dynamic Language Runtime has been added, which will act as a useful bridge to such languages as IronPython and IronRuby. The DLR optimizes dynamic languages at runtime for better performance with .Net. Also added is the dynamic pseudo-type, which allows run-time lookup of properties and methods on dynamic and compiled types. This will assist in the usage of dynamic code from compiled code, and also fits into some polymorphism scenarios. There are also a number of Base Core Library changes.
C# will be gaining some new language functionality with the .Net 4.0 release. C# now supports option parameters, named parameters and default parameter values to assist with those situations where overloads are cumbersome. C# 4.0 also supports a type of covariance and contravariance for collections.
The .Net 4.0 framework was delayed because of performance issues. I am glad they waited to get it right.
Silverlight 4.0 is scheduled to be released later this week. ASP.Net MVC 2.0 was released a couple of weeks ago, which takes advantages of a couple of new .Net 4.0 scenarios.
