Thanks to attendees of my Introduction to Linq as a Language Feature talk.

Here is a LINQ to a zip file with my presentation and all sample LinqPad files.

Here are a set of LINQs covered in the talk.

• Test what you have learned about LINQ by taking the LINQ quiz!


• LinqPad, a wonderful tool used heavily in this talk.


• A really lucid explanation of grouping in LINQ


• An explanation of common gotcha with Linq, and really .NET in general, is the need to implement GetHashCode to deal with an equality check . This is a good example of the pain that you can go through, but take this lesson: implement GetHashCode!


• This is a nice explanation of how to deal with the possibility of an IEnumerable that contains no elements. Stack Overflow has many great LINQ questions, often answered by Jon Skeet. An excerpt from this post is "Use First when you know that there is one or more items in the collection. Use Single when you know that there is exactly one item in the collection. If you don't know those things, then don't use those methods. Use methods that do something else, like FirstOrDefault(), SingleOrDefault() and so on."


• An excellent book, Linq In Action has code samples that plug in directly to Linqpad.


• Hooked on Linq offers a brief introduction to LINQ. The author also has written a book Linq to Objects Using C# 4.0.


• Microsoft has published 101 LINQ examples.


• You can't research LINQ much without running into Jon Skeet's work. He has a new training series on C# at Tekpubthat takes a gentler approach. Beyond that, if you really want a deep understanding of C# features and LINQ. This material, particularly his blog and presentations, can be rather challenging. If you are up for the challenge, I have found it to be very rewarding.


• The Interactive LINQ project from Microsoft is still in an early stage but is worth checking out. Here is an overview of the project.


• LINQ can be considered a pull technology like most database access approaches. Microsoft has provided a set of Reactive Extensions that provide push technology, kind of like SQL Server Query Notifications.


• If you'd like to read more about LINQ to WMI, here is my codeproject article.


• Here is a helpful presentation on closures by Stuart Langridge. It is in Javascript, but the sample concepts apply.


• Linq perspectives from Bart De Smet.