Why is "Evaluation of lambda expressions is not valid in the debugger"?

Question

I have a seemingly innocent code snippet, which I typed into Visual Studio 2008 Immediate Window.

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Evaluation of lambda expressions is not valid in the debugger.

As the message says, it's not possible to call a lambda expression in the debugger.
Why is it not allowed?

score 5 · Accepted Answer · edited May 23 '17 at 12:25

5

Here: Why is LINQ absent from debugger windows?

And this previous question: VS debugging “quick watch” tool and lambda expressions

In short, complexity.

edited May 23 '17 at 12:25

Community

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answered Dec 15 '09 at 15:03

jason

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@Jason: Your summary sums it up right, according to what I read. Thanks. – dance2die Dec 15 '09 at 15:17
Really, really missing the capability of a Rails console in making this transition to EF/.NET. – David Krider Apr 11 '14 at 13:29

score 1 · Answer 2 · answered Dec 15 '09 at 15:02

http://msdn.microsoft.com/en-us/library/bb763138.aspx

It's impossible by design. Lambda expressions need to generate code on the fly in the immediate window. The debugger and/or evaluater cannot handle this. If you really want to know why, ask the developers of VS. Maybe this is an upcoming feature somewhen. Lambda expressions is a bearly new feature

Why is "Evaluation of lambda expressions is not valid in the debugger"?

2 Answers2

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