Where is Microsoft.Scripting.Core.dll?

Question

I installed IronPython 2.6.1 on Windows Vista x64 on a machine with Visual Studio 2010 installed. I expected to find these DLLs:

Microsoft.Scripting.Core.dll
Microsoft.Scripting.ExtensionAttribute.dll

... in the IronPython directory, but they are not there.

Is this a difference between IronPython 2.6.0 and 2.6.1 or do I have a problem with my installation?

Edit

It has been suggested that I edit this question to explain why it is not a duplicate of How to use Microsoft.Scripting.Hosting?

The two questions are both about problems referencing Iron Python libraries from C# projects.

However this question is about a problem encountered upgrading a C# project from Iron Python 2.6.0 to a later version. Note the comment below: "I found a lot of posts (discussing the .NET 2.0 SP1 version) containing statements that are now outdated". This question is about .NET 4.0 version, not .NET version 3.5 which builds on the .NET 2.0 CLR.

The unresolved library names provide a distinctive signature to a search engine therefore the specific search terms leading to the question are different. The technical details such as library names, Visual Studio, C# and .NET versions are all different and the problem being solved (library upgrade vs new project setup) is different.

The root cause of both questions is the migration of DLR libraries into the CLR over successive releases, but the problem being solved in each case is specific to the individual question.

Answer 1

Those assemblies implemented the DLR. That's been moved in .NET 4.0, System.Core.dll assembly.

Answer 2

I have 2.6.1 for .NET 4.0 installed and those assemblies are not available since, if I'm not mistaken, they were integrated into .NET 4.0 System.Core.

Those assemblies are still available in the .NET 2.0 version of IronPython 2.6.1.