1. F# Eye 4 the C# Guy
Phil Trelford, @ptrelford
#dddnorth, Sunderland 2013

2. Visual F#

3. The F in F# stands for FUN!

4. Halo 3 with F# Skills

5. XBLA: Path to Go – F# AI

6. Facebook: Monopoly

7. F#
• Statically Typed
• Functional First
• Object Orientated
• Open Source
• .Net language
• In Visual Studio
& Xamarin Studio

8. F# for Profit: Kaggle
The F# code is
consistently shorter,
easier to read,
easier to refactor and
contains far fewer bugs.
…we’ve become
more productive.

9. LIVE DEMOS
Phil Trelford, @ptrelford
DDD North, Sunderland 2013

10. Light Syntax: POCOs
F#
type Person(name:string,age:int) =
/// Full name
member person.Name = name
/// Age in years
member person.Age = age
C#
public class Person
{
public Person(string name, int age)
{
_name = name;
_age = age;
}
private readonly string _name;
private readonly int _age;
/// <summary>
/// Full name
/// </summary>
public string Name
{
get { return _name; }
}
/// <summary>
/// Age in years
/// </summary>
public int Age
{
get { return _age; }
}
}

11. Light Syntax: DI
F#
type VerySimpleStockTrader
(analysisService:IStockAnalysisService,
brokerageService:IOnlineBrokerageService) =
member this.ExecuteTrades() =
() // ...
C#
public class VerySimpleStockTrader
{
private readonly
IStockAnalysisService analysisService;
private readonly
IOnlineBrokerageService brokerageService;
public VerySimpleStockTraderImpl(
IStockAnalysisService analysisService,
IOnlineBrokerageService brokerageService)
{
this.analysisService = analysisService;
this.brokerageService = brokerageService;
}
public void ExecuteTrades()
{
// ...
}
}

12. Unit Testing
F# NUnit
module MathTest =
open NUnit.Framework
let [<Test>] ``2 + 2 should equal 4``() =
Assert.AreEqual(2 + 2, 4)
C# NUnit
using NUnit.Framework;
[TestFixture]
public class MathTest
{
[Test]
public void
TwoPlusTwoShouldEqualFour()
{
Assert.AreEqual(2 + 2, 4);
}
}

13. Mocking
F# Foq
let [<Test>] ``order sends mail if unfilled``() =
// setup data
let order = Order("TALISKER", 51)
let mailer = mock()
order.SetMailer(mailer)
// exercise
order.Fill(mock())
// verify
verify <@ mailer.Send(any()) @> once
C# Moq
public void OrderSendsMailIfUnfilled()
{
// setup data
var order = new Order("TALISKER", 51);
var mailer = new Mock<MailService>();
order.SetMailer(mailer.Object);
// exercise
order.Fill(Mock.Of<Warehouse>());
// verify
mailer.Verify(mock =>
mock.Send(It.IsAny<string>()),
Times.Once());
}

14. Tickspec: Debugging

15. Mario Tutorial

16. Pacman with FunScript

17. RESOURCES
Phil Trelford, @ptrelford
DDD North, Sunderland 2013

18. Try F#:
http://tryfsharp.org

19. Buy the Book

20. Get the T-Shirt

21. Show me the money!

22. Questions?
Twitter:
@ptrelford
Blog:
http://trelford.com/blog
F# Foundation:
http://fsharp.org