using System.IO;
using System.Web.Mvc;

namespace MVC4Basic.Controllers
{
    public class HomeController : Controller
    {
        public ActionResult Index()
        {
            return View();
        }

        const int AMonth = 30 * 86400;

        [OutputCache(Duration = AMonth, VaryByParam = "name")]
        public ActionResult GetImage(string name)
        {
            name = Path.GetFileName(name);
            var path = Server.MapPath(string.Format("~/app_data/images/{0}", name));
            var content = System.IO.File.ReadAllBytes(path);
            return File(content, "image/png", name);
        }
    }
}

 <img src="@Url.Action("GetImage","Home", new { name = "test.png"})"/>

 Remote Address:127.0.0.1:5656
Request URL:http://localhost:10419/Home/GetImage?name=test.png
Request Method:GET
Status Code:200 OK

Response Headers
Cache-Control:public, max-age=2591916
Expires:Sat, 31 May 2014 12:45:55 GMT
Last-Modified:Thu, 01 May 2014 12:45:55 GMT

 Remote Address:127.0.0.1:5656
Request URL:http://localhost:10419/Home/GetImage?name=test.png
Request Method:GET
Status Code:304 Not Modified

Request Headers
If-Modified-Since:Thu, 01 May 2014 12:45:55 GMT

 Remote Address:127.0.0.1:5656
Request URL:http://localhost:10419/Home/GetImage?name=test.png
Request Method:GET
Status Code:200 OK (from cache)

 Remote Address:127.0.0.1:5656
Request URL:http://localhost:10419/Home/GetImage?name=test.png
Request Method:GET
Status Code:200 OK

Request Headers
If-Modified-Since:Thu, 01 May 2014 12:45:55 GMT

using System;
using System.IO;
using System.Net;
using System.Web.Mvc;

namespace MVC4Basic.Controllers
{
    public class HomeController : Controller
    {
        public ActionResult Index()
        {
            return View();
        }

        const int AMonth = 30 * 86400;

        [OutputCache(Duration = AMonth, VaryByParam = "name")]
        public ActionResult GetImage(string name)
        {
            name = Path.GetFileName(name);
            var path = Server.MapPath(string.Format("~/app_data/images/{0}", name));

            var lastWriteTime = System.IO.File.GetLastWriteTime(path);
            this.Response.Cache.SetLastModified(lastWriteTime.ToUniversalTime());

            var header = this.Request.Headers["If-Modified-Since"];
            if (!string.IsNullOrWhiteSpace(header))
            {
                DateTime isModifiedSince;
                if (DateTime.TryParse(header, out isModifiedSince) && isModifiedSince > lastWriteTime)
                {
                    return new HttpStatusCodeResult(HttpStatusCode.NotModified);
                }
            }

            var content = System.IO.File.ReadAllBytes(path);
            return File(content, "image/png", name);
        }
    }
}

 Remote Address:127.0.0.1:5656
Request URL:http://localhost:10419/Home/GetImage?name=test.png
Request Method:GET
Status Code:304 Not Modified

Request Headers
If-Modified-Since:Thu, 01 May 2014 13:43:32 GMT

    [AttributeUsage(AttributeTargets.Method, AllowMultiple = false)]
    public sealed class SetIfModifiedSinceAttribute : ActionFilterAttribute
    {
        public string Parameter { set; get; }
        public string BasePath { set; get; }

        public override void OnActionExecuting(ActionExecutingContext filterContext)
        {
            var response = filterContext.RequestContext.HttpContext.Response;
            var request = filterContext.RequestContext.HttpContext.Request;

            var path = getPath(filterContext);
            if (string.IsNullOrWhiteSpace(path))
            {
                response.StatusCode = (int)HttpStatusCode.NotFound;
                filterContext.Result = new EmptyResult();
                return;
            }

            var lastWriteTime = File.GetLastWriteTime(path);
            response.Cache.SetLastModified(lastWriteTime.ToUniversalTime());

            var header = request.Headers["If-Modified-Since"];
            if (string.IsNullOrWhiteSpace(header)) return;
            DateTime isModifiedSince;
            if (DateTime.TryParse(header, out isModifiedSince) && isModifiedSince > lastWriteTime)
            {
                response.StatusCode = (int)HttpStatusCode.NotModified;
                response.SuppressContent = true;
                filterContext.Result = new EmptyResult();
            }
        }

        string getPath(ActionExecutingContext filterContext)
        {
            if (!filterContext.ActionParameters.ContainsKey(Parameter)) return string.Empty;
            var name = filterContext.ActionParameters[Parameter] as string;
            if (string.IsNullOrWhiteSpace(name)) return string.Empty;

            var path = Path.GetFileName(name);
            path = filterContext.HttpContext.Server.MapPath(string.Format("{0}/{1}", BasePath, path));
            return !File.Exists(path) ? string.Empty : path;
        }
    }

        [SetIfModifiedSince(Parameter = "name", BasePath = "~/app_data/images/")]
        [OutputCache(Duration = AMonth, VaryByParam = "name")]
        public ActionResult GetImage(string name)
        {
            name = Path.GetFileName(name);
            var path = Server.MapPath(string.Format("~/app_data/images/{0}", name));
            var content = System.IO.File.ReadAllBytes(path);
            return File(content, "image/png", name);
        }

ReSharper 2021.1: Updates in Code Analysis, Support for ASP.NET Route Templates, and Rename for Tuple Components 

C# 11 is the next version of C# coming in .NET 7, and it is introducing a warning wave that issues a warning when a type is declared with all lower-case letters. This is being done so that in the future the language can begin moving away from conditional keywords and instead use full on keywords instead. The warning is alerting customers to types that may become keywords in future versions. 

type [access-modifier] type-name [type-params] [access-modifier] ( parameter-list ) [ as identifier ] =
   [ class ]
     [ inherit base-type-name(base-constructor-args) ]
     [ let-bindings ]
     [ do-bindings ]
     member-list
      ...
   [ end ]

type [access-modifier] type-name1 ...
and [access-modifier] type-name2 ...
...

type Account(number : int, name : string) = class
    let mutable amount = 0m
   
end

let myAccount = new Account(123456, "Masoud")

type Account(number : int, name: string) = class
    let mutable amount = 0m
 
    member x.Number = number
    member x.Name= name
    member x.Amount = amount
 
    member x.Deposit(value) = amount <- amount + value
    member x.Withdraw(value) = amount <- amount - value
end

open System
 
type Account(number : int, name: string) = class
    let mutable amount = 0m
 
    member x.Number = number
    member x.Name= name
    member x.Amount = amount
 
    member x.Deposit(value) = amount <- amount + value
    member x.Withdraw(value) = amount <- amount - value
end



 let masoud= new Account(12345, "Masoud")
 let saeed = new Account(67890, "Saeed")
 
let transfer amount (source : Account) (target : Account) =
    source.Withdraw amount
    target.Deposit amount
 
let printAccount (x : Account) =
    printfn "x.Number: %i, x.Name: %s, x.Amount: %M" x.Number x.Name x.Amount
 
let main() =
    let printAccounts() =
        [masoud; saeed] |> Seq.iter printAccount
 
    printfn "\nInializing account"
    homer.Deposit 50M
    marge.Deposit 100M
    printAccounts()
 
    printfn "\nTransferring $30 from Masoud to Saeed"
    transfer 30M masoud saeed



    printAccounts()
 
    printfn "\nTransferring $75 from Saeed to Masoud"
    transfer 75M saeed masoud
    printAccounts()
 
main()

open System
open System.Net
 
type Stock(symbol : string) = class

    let mutable _symbol = String.Empty
    do
     //کد مورد نظر در این جا نوشته  میشود
end

open System

type MyType(a:int, b:int) as this =
    inherit Object()
    let x = 2*a
    let y = 2*b
    do printfn "Initializing object %d %d %d %d %d %d"
               a b x y (this.Prop1) (this.Prop2)
    static do printfn "Initializing MyType." 
    member this.Prop1 = 4*x
    member this.Prop2 = 4*y
    override this.ToString() = System.String.Format("{0} {1}", this.Prop1, this.Prop2)

let obj1 = new MyType(1, 2)

Initializing MyType.
Initializing object 1 2 2 4 8 16

type SomeClass(prop : int) = class
    member x.Prop = prop
    static member SomeStaticMethod = "This is a static method"
end

let instance = new SomeClass(5);;
instance.SomeStaticMethod;; 

output:
stdin(81,1): error FS0191: property 'SomeStaticMethod' is static.

SomeClass.SomeStaticMethod;; (* invoking static method *)

 member alias.PropertyName
        with get() = some-value
        and set(value) = some-assignment

type MyClass() = class
   let mutable num = 0 
    member x.Num
        with get() = num
        and set(value) = num <- value
end;;

public int Num
{
   get{return num;}
   set{num=value;}
}

type MyClass() = class
    let mutable num = 0
 
    member x.Num
        with get() = num
        and set(value) =
            if value > 10 || value < 0 then
                raise (new Exception("Values must be between 0 and 10"))
            else
                num <- value
end

type type-name = 
   interface
       inherits-decl 
       member-defns 
   end

type IPrintable =
   abstract member Print : unit -> unit

type SomeClass1(x: int, y: float) =
   interface IPrintable with 
      member this.Print() = printfn "%d %f" x y

let instance = new SomeClass1(10,20)
instance.Print//فراخوانی این متد باعث ایجاد خطای کامپایلری می‌شود.

let instance = new SomeClass1(10,20) 
let instanceCast = instance :> IPrintable// استفاده از (<:)  برای عملیات تبدیل کلاس به اینترفیس
instanceCast.Print

type Interface1 =
    abstract member Method1 : int -> int

type Interface2 =
    abstract member Method2 : int -> int

type Interface3 =
    inherit Interface1
    inherit Interface2
    abstract member Method3 : int -> int

type MyClass() =
    interface Interface3 with 
        member this.Method1(n) = 2 * n
        member this.Method2(n) = n + 100
        member this.Method3(n) = n / 10

let instance = new MyClass()
let instanceToCast = instance :> Interface3
instanceToCast.Method3 10

[<AbstractClass>]
type [ accessibility-modifier ] abstract-class-name =
    [ inherit base-class-or-interface-name ]
    [ abstract-member-declarations-and-member-definitions ]

    abstract member member-name : type-signature

[<AbstractClass>]
type Shape(x0 : float, y0 : float) =
    let mutable x, y = x0, y0
    let mutable rotAngle = 0.0

    abstract Area : float with get
    abstract Perimeter : float  with get
    abstract Name : string with get

type Square(x, y,SideLength) =
    inherit Shape(x, y)





   override this.Area = this.SideLength * this.SideLength
    override this.Perimeter = this.SideLength * 4.
    override this.Name = "Square"

type Circle(x, y, radius) =
    inherit Shape(x, y)



    let PI = 3.141592654
    member this.Radius = radius
    override this.Area = PI * this.Radius * this.Radius
    override this.Perimeter = 2. * PI * this.Radius

[ attributes ]
type [accessibility-modifier] type-name =
   struct
      type-definition-elements
   end

//یا به صورت زیر

[ attributes ]
[<StructAttribute>]
type [accessibility-modifier] type-name =
   type-definition-elements

type Point3D =
   struct 
      val x: float
      val y: float
      val z: float
   end

type Point2D =
   struct 
      val X: float
      val Y: float
      new(x: float, y: float) = { X = x; Y = y }
   end

• الف) زبان مدل سازی M
• ب) ابزار مدل سازی Quadrant
• ج) استفاده از SQL Server به عنوان مخزن

module Test1
{
  type ApplicationUser
  {
      UserID : Integer64=AutoNumber();
      FirstName :Text#15;
      LastName : Text#25;
      Password : Text#10;
  } where identity UserID;      
}

ApplicationUserCollection : ApplicationUser*;

  ApplicationUserCollection
  {
      //using a named instance
      User1 {
          FirstName="user1",
          LastName="name1",
          Password="1@34"
          },
          User2 {
          FirstName="user2",
          LastName="name2",
          Password="123@4"
          },
      User3 {
          FirstName="user3",
          LastName="name3",
          Password="56#2"
          },
      User4 {
          FirstName="user4",
          LastName="name4",
          Password="789@5"
          }
  }  

A React-like user interface micro-library