Functors when should I use them whats their intended use [closed]

Answer 1

I'm sure you mean Lambda Expressions. Those are Small Functions you can write very quickly, and they have the characteristic "=>" Operator. These are a new Feature of C# 3.0.

This Example will be a classic Transformer; to use one we need a delegate to define the signature for the Lambda Function.

delegate int Transformer(int i);

Now Declare a Lambda with this delegate:

Transformer sqr = x => x * x;

We can use it like a normal function:

Console.WriteLine(sqr(3)); //9

These are used in LINQ Queries a lot, for example to Sort (Comparer), to Search through (Predicate).

The book "C# Pocket Reference" (apart from beign the best around in my opinion, has a very good part on Lambdas. (ISBN 978-0-596-51922-3 )