open System.Net.Http
open System
type RequestBuilder()=

      member this.Combine (a:HttpRequestMessage->HttpRequestMessage,b:HttpRequestMessage->HttpRequestMessage) = a>>b
      member this.Yield (())=fun r->r
      member this.Yield (r:HttpRequestMessage->HttpRequestMessage)=r

      member this.Delay(f)=f()

      [<CustomOperation("method")>]
      member this.Method(f:HttpRequestMessage->HttpRequestMessage,m:HttpMethod)=
        fun r->
         let request=f(r)
         request.Method<-m
         request
      [<CustomOperation("header")>]
      member this.Header(f:HttpRequestMessage->HttpRequestMessage,name:string,value:string)=
       fun r->
        let request=f(r)
        request.Headers.Add(name,value)
        request
      [<CustomOperation("url")>]
      member this.Url (f:HttpRequestMessage->HttpRequestMessage,uri)=
       fun r->
        let request=f(r)
        request.RequestUri<-new Uri(uri)
        request

[<EntryPoint>]
let main argv =
    let req  =RequestBuilder()

    let request=req
                   {
                      method HttpMethod.Get
                      url "http://lenta.ru"
                      header "Authorization" "Basic"
                      header "MyHeader" "MyValue"
                   }

    let req2=req
                   {
                      method HttpMethod.Delete
                      url "http://j.ru"

                   }
    let getBuilder=req {method HttpMethod.Get}
    let headers= req{
                     header "Authorization" "Basic"
                     header "MyHeader" "MyValue"
                   }


    let r1=req{
                 yield getBuilder
                 yield headers
              }
    printfn "%A" argv
    let r2=new HttpRequestMessage()|>r1
    0 // return an integer exit code