# Func and Action

A delegate is a reference type that is used to encapsulates an anonymous or named method.

This is the way of C# uses to allow the creation of high order functions and to turn possible treat methods as a first class member.

There's a lot of delegates embedded in C# language, but two of them are very important for functional development and for **Tango**.

They are: `Func` and `Action` delegates.

These two delegates can be used to represents any method presents in your code, with a single, but very important difference.

The `Func` delegate is only capable of encapsulate methods that creates a result, that is, all methods needs to return a new value.

While the `Action` delegate is capable of encapsulate methods that **don't** creates a result, that is, `void` methods.

There´s a lot of overloads of these two delegates in order to coverage any quantity of parameters, from 0 to 16.

For instance, see how `Func` delegates can be used to store a method:

```csharp
Func<int,int,int> Add = (number1, number2) => number1 + number2;
```

Because of its overloads these delegates can be use to represents a lot of different methods.

In this next sample, an bool method will be encapsulated:

```csharp
Func<int,bool> IsEven = number => number % 2 == 0;
```

Notice that the last type passed to *generics* in \`Func 'delegate represents the type of value returned by the function, and the previous ones are used to represent the types of each parameter respectively.

The same occurs to the `Action` delegate, but at this time we have no return.

```csharp
Action<double> WriteNumber = number => Console.WriteLine(number);
```

The `System.Linq` namespace, uses a lot of this concept to create powerful high order functions, like the **Tango** do. In order to create high order functions to improve your code, turning it more expressive and clean.


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