Editing Constructor (object-oriented programming) (section)

=== F# ===
In [[F Sharp (programming language)|F#]], a constructor can include any <code>let</code> or <code>do</code> statements defined in a class. <code>let</code> statements define private fields and <code>do</code> statements execute code. Additional constructors can be defined using the <code>new</code> keyword.

<syntaxhighlight lang="fsharp">
type MyClass(_a : int, _b : string) = class
    // Primary constructor
    let a = _a
    let b = _b
    do printfn "a = %i, b = %s" a b

    // Additional constructors
    new(_a : int) = MyClass(_a, "") then
        printfn "Integer parameter given"

    new(_b : string) = MyClass(0, _b) then
        printfn "String parameter given"

    new() = MyClass(0, "") then
        printfn "No parameter given"
end
</syntaxhighlight>

<syntaxhighlight lang = "fsharp">
// Code somewhere
// instantiating an object with the primary constructor
let c1 = new MyClass(42, "string")

// instantiating an object with additional constructors
let c2 = new MyClass(42)
let c3 = new MyClass("string")
let c4 = MyClass() // "new" keyword is optional
</syntaxhighlight>