Editing F Sharp (programming language) (section)

===Object-oriented programming===
Like other [[Common Language Infrastructure]] (CLI) languages, F# can use CLI types through object-oriented programming.<ref name="overview"/> F# support for object-oriented programming in expressions includes:
* Dot-notation, e.g., {{code|lang=fsharp|code=x.Name}}
* Object expressions, e.g., {{ code|lang=fsharp| code={ new obj() with member x.ToString() = "hello" } }}
* Object construction, e.g., {{code|lang=fsharp|code=new Form()}}
* Type tests, e.g., {{code|lang=fsharp|code=x :? string}}
* Type coercions, e.g., {{code|lang=fsharp|code=x :?> string}}
* Named arguments, e.g., {{code|lang=fsharp|code=x.Method(someArgument=1)}}
* Named setters, e.g., {{code|lang=fsharp|code=new Form(Text="Hello")}}
* Optional arguments, e.g., {{code|lang=fsharp|code=x.Method(OptionalArgument=1)}}

Support for object-oriented programming in patterns includes
* Type tests, e.g., {{code|lang=fsharp|code=:? string as s}}
* Active patterns, which can be defined over object types<ref name="activePatterns">{{cite web |url=http://www.developerfusion.com/article/133772/pattern-matching-in-f-part-2-active-patterns/ |title=Pattern Matching in F# Part 2 : Active Patterns |access-date=2012-11-24 |archive-date=2012-12-09 |archive-url=https://web.archive.org/web/20121209125518/http://www.developerfusion.com/article/133772/pattern-matching-in-f-part-2-active-patterns |url-status=dead}}</ref>

F# object type definitions can be class, struct, interface, enum, or delegate type definitions, corresponding to the definition forms found in [[C Sharp (programming language)|C#]]. For example, here is a class with a constructor taking a name and age, and declaring two properties.
<syntaxhighlight lang="fsharp">
/// A simple object type definition
type Person(name : string, age : int) =
    member x.Name = name
    member x.Age = age
</syntaxhighlight>