.NET Framework 4.0

C# v4.0 - Visual Studio 2010

System.Lazy <T>

Lazy instantiation defers the creation of an object until it is actually accessed.
Object creation is always expensive because it involves allocation of memory on the heap

.NET Framework 4.0

VSTO - Parameterized Properties

System.Tuple

System.Collections.Generic.SortedSet

Optional Parameters

Named Parameters

Dynamic/Late Binding - dynamic

Type Variance

Embedded PIAs

System.Threading.Task

System.Numerics

System.Lazy <T>