F#

// This is a comment for a sample hello world program.printfn "Hello World!"

/// This is a documentation comment for a type definition.type Person(name : string, age : int) =    member x.Name = name    member x.Age = age    /// class instantiationlet mrSmith = Person("Smith", 42)

/// Using pattern matching expressionlet rec factorial n =    match n with    | 0 -> 1    | _ -> n * factorial (n - 1)/// For a single-argument functions there is syntactic sugar (pattern matching function):let rec factorial = function     | 0 -> 1     | n -> n * factorial (n - 1)    /// Using fold and range operatorlet factorial n =  |> Seq.fold (*) 1

/// Iteration using a 'for' looplet printList lst =     for x in lst do        printfn "%d" x/// Iteration using a higher-order functionlet printList2 lst =     List.iter (printfn "%d") lst/// Iteration using a recursive function and pattern matchinglet rec printList3 lst =    match lst with    |  -> ()    | h :: t ->        printfn "%d" h        printList3 t

斐波那契数列数列示例：

/// Fibonacci Number formulalet fib n =    let rec g n f0 f1 =        match n with        | 0 -> f0        | 1 -> f1        | _ -> g (n - 1) f1 (f0 + f1)    g n 0 1/// Another approach - a lazy infinite sequence of Fibonacci numberslet fibSeq = Seq.unfold (fun (a,b) -> Some(a+b, (b, a+b))) (0,1)// Print even fibs|> List.map     fib|> List.filter  (fun n -> (n % 2) = 0)|> printList// Same thing, using a list expression|> printList

一个Windows程序样本示例:

// Open the Windows Forms libraryopen System.Windows.Forms// Create a window and set a few propertieslet form = new Form(Visible=true, TopMost=true, Text="Welcome to F#")// Create a label to show some text in the formlet label =    let x = 3 + (4 * 5)    new Label(Text = sprintf "x = %d" x)// Add the label to the formform.Controls.Add(label)// Finally, run the formApplication.Run(form)

多线程编程示例（此处为CPU和I/O任务同时进行）:

/// A simple prime number detectorlet isPrime (n:int) =   let bound = int (sqrt (float n))   seq {2 .. bound} |> Seq.forall (fun x -> n % x <> 0)// We are using async workflowslet primeAsync n =    async { return (n, isPrime n) }/// Return primes between m and n using multiple threadslet primes m n =    seq {m .. n}        |> Seq.map primeAsync        |> Async.Parallel        |> Async.RunSynchronously        |> Array.filter snd        |> Array.map fst// Run a testprimes 1000000 1002000    |> Array.iter (printfn "%d")

参考文献

外部链接

• 微软F#（页面存档备份，存于互联网档案馆）
• F Sharp
• Planet F#
• （英文）F#（页面存档备份，存于互联网档案馆）