Why would you use Expression> rather than Func?

Question

I understand lambdas and the Func and Action delegates. But expressions stump me.

In what circumstances would you use an Expression

Answer 1

I'd like to add some notes about the differences between Func and Expression>:

• Func is just a normal old-school MulticastDelegate;
• Expression> is a representation of lambda expression in form of expression tree;
• expression tree can be constructed through lambda expression syntax or through the API syntax;
• expression tree can be compiled to a delegate Func;
• the inverse conversion is theoretically possible, but it's a kind of decompiling, there is no builtin functionality for that as it's not a straightforward process;
• expression tree can be observed/translated/modified through the ExpressionVisitor;
• the extension methods for IEnumerable operate with Func;
• the extension methods for IQueryable operate with Expression>.

There's an article which describes the details with code samples:
LINQ: Func vs. Expression>.

Hope it will be helpful.