Dynamic Language Runtime

The Dynamic Language Runtime (DLR) from Microsoft runs on top of the Common Language Runtime and provides computer language services for several different dynamic languages. These services include:

The DLR is used to implement dynamic languages on the .NET Framework, specifically by IronPython and IronRuby projects.

By having several dynamic language implementations share a common underlying system, it should be easier to let these implementations interact with one another. For example, it should be possible to use libraries from any dynamic language in any other dynamic language. In addition, the hosting API allows interoperability with statically typed CLI languages like C# and Visual Basic .NET.

Microsoft's Dynamic Language Runtime project was announced by Microsoft at MIX 2007.

Microsoft shipped .NET DLR 0.9 beta on the 26 November 2008, and final 0.9 on 10 December 2008. Version 1.0 shipped on April 16, 2010. On 16 July 2010, Microsoft changed the license of the DLR from the Microsoft Public License to the Apache License, v2.0. With the release of .NET 4, also in April 2010, DLR was incorporated into the .NET Framework itself.

The open source DLR project hosted on CodePlex has a few additional features for language implementers, but there has been no activity on the project since the July 2010 release, which could be linked to what some, including a Microsoft developer who worked for IronRuby, saw as a lack of commitment from Microsoft to dynamic languages on the .NET Framework.

The DLR services are currently used in the development version of IronRuby, a .NET implementation of the Ruby language, and for IronPython.