The Project | About Us | Contribute | Donations | License
HOME My courses Completed
◄ Previous
◄

Interoperability with C#

End!

Introduction

F# is a powerful functional-first language that runs on the .NET platform, which means it can interoperate seamlessly with C#. This interoperability allows developers to leverage existing C# libraries and frameworks within F# projects and vice versa. In this section, we will explore how to call C# code from F# and how to call F# code from C#.

Key Concepts

  1. Referencing C# Assemblies in F# Projects
  2. Calling C# Methods from F#
  3. Using C# Classes and Objects in F#
  4. Handling C# Events in F#
  5. Referencing F# Assemblies in C# Projects
  6. Calling F# Functions from C#
  7. Using F# Types in C#

Referencing C# Assemblies in F# Projects

To use C# code in an F# project, you need to reference the C# assembly. This can be done in the project file (.fsproj) or through the IDE.

Example

  1. Add Reference in .fsproj File:
<ItemGroup>
  <ProjectReference Include="..\CSharpProject\CSharpProject.csproj" />
</ItemGroup>

  1. Add Reference in Visual Studio:

    • Right-click on the F# project in Solution Explorer.
    • Select "Add" > "Reference..."
    • Choose the C# project or assembly.

Calling C# Methods from F#

Once the reference is added, you can call C# methods directly from F#.

Example

Assume we have a C# class Calculator in a C# project:

// CSharpProject/Calculator.cs
namespace CSharpProject
{
    public class Calculator
    {
        public int Add(int a, int b)
        {
            return a + b;
        }
    }
}

You can call this method from F# as follows:

// FSharpProject/Program.fs
open CSharpProject

[<EntryPoint>]
let main argv =
    let calculator = Calculator()
    let result = calculator.Add(3, 5)
    printfn "The result is %d" result
    0

Using C# Classes and Objects in F#

F# can instantiate and use C# classes and objects just like any other .NET language.

Example

Assume we have a C# class Person:

// CSharpProject/Person.cs
namespace CSharpProject
{
    public class Person
    {
        public string Name { get; set; }
        public int Age { get; set; }

        public Person(string name, int age)
        {
            Name = name;
            Age = age;
        }

        public void Greet()
        {
            Console.WriteLine($"Hello, my name is {Name} and I am {Age} years old.");
        }
    }
}

You can use this class in F#:

// FSharpProject/Program.fs
open CSharpProject

[<EntryPoint>]
let main argv =
    let person = Person("Alice", 30)
    person.Greet()
    0

Handling C# Events in F#

F# can subscribe to and handle events defined in C#.

Example

Assume we have a C# class with an event:

// CSharpProject/Notifier.cs
namespace CSharpProject
{
    public class Notifier
    {
        public event EventHandler Notification;

        public void Notify()
        {
            Notification?.Invoke(this, EventArgs.Empty);
        }
    }
}

You can handle this event in F#:

// FSharpProject/Program.fs
open System
open CSharpProject

[<EntryPoint>]
let main argv =
    let notifier = Notifier()
    notifier.Notification.Add(fun _ -> printfn "Notification received!")
    notifier.Notify()
    0

Referencing F# Assemblies in C# Projects

To use F# code in a C# project, you need to reference the F# assembly.

Example

  1. Add Reference in .csproj File:
<ItemGroup>
  <ProjectReference Include="..\FSharpProject\FSharpProject.fsproj" />
</ItemGroup>

  1. Add Reference in Visual Studio:

    • Right-click on the C# project in Solution Explorer.
    • Select "Add" > "Reference..."
    • Choose the F# project or assembly.

Calling F# Functions from C#

F# functions can be called from C# if they are defined in a module or a class.

Example

Assume we have an F# module with a function:

// FSharpProject/Math.fs
module Math

let add a b = a + b

You can call this function from C#:

// CSharpProject/Program.cs
using System;
using FSharpProject;

class Program
{
    static void Main()
    {
        int result = Math.add(3, 5);
        Console.WriteLine($"The result is {result}");
    }
}

Using F# Types in C#

F# types such as records and discriminated unions can be used in C#.

Example

Assume we have an F# record type:

// FSharpProject/Types.fs
namespace FSharpProject

type Person = { Name: string; Age: int }

You can use this type in C#:

// CSharpProject/Program.cs
using System;
using FSharpProject;

class Program
{
    static void Main()
    {
        var person = new Person("Alice", 30);
        Console.WriteLine($"Name: {person.Name}, Age: {person.Age}");
    }
}

Practical Exercise

Exercise

  1. Create a C# class Multiplier with a method Multiply that takes two integers and returns their product.
  2. Create an F# project that references the C# project.
  3. Call the Multiply method from F# and print the result.

Solution

  1. C# Class:
// CSharpProject/Multiplier.cs
namespace CSharpProject
{
    public class Multiplier
    {
        public int Multiply(int a, int b)
        {
            return a * b;
        }
    }
}
  1. F# Code:
// FSharpProject/Program.fs
open CSharpProject

[<EntryPoint>]
let main argv =
    let multiplier = Multiplier()
    let result = multiplier.Multiply(4, 5)
    printfn "The result is %d" result
    0

Conclusion

In this section, we explored how to achieve interoperability between F# and C#. We covered referencing assemblies, calling methods, using classes and objects, handling events, and using types across both languages. This interoperability allows developers to leverage the strengths of both languages in a single project, enhancing productivity and code reuse.

◄ Previous
◄
End!
The Project | About Us | Contribute | Donations | License
© Copyright 2024. All rights reserved