"LINQ Framework Design Guidelines"

Mircea Trofin's blog - LINQ Framework Design Guidelines

"Writing applications that interact with data sources, such as databases, XML documents, or Web Services such as Flickr or Amazon, is made easier in the .NET Framework 3.5 with the addition of a set of features collectively referred to as LINQ (Language-Integrated Query). In what follows, we start with a very brief overview of LINQ, followed by guidelines for designing APIs in relation to LINQ.

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2. Extension Methods, Func<>, Action<>, and Expression<>

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3. Extending on LINQ

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You know me, a sucker for Design Guidelines. This, or more likely a future version of, could very well also be in the future Framework Design Guidelines edition

(via Krzysztof Cwalina - LINQ Design Guidelines)