type System.Int32 with

    member this.Lsl(idx) = if (idx > 31) || (idx < 0) then 0 else this <<< idx

    member this.Lsr(idx) = if (idx > 31) || (idx < 0) then 0 else int32 ((uint32 this) >>> idx)

    member this.Asr(idx) = if (idx > 31) || (idx < 0) then 0 else this >>> idx

    member this.Ror(idx) = (this.Lsr(idx &&& 31)) ||| (this.Lsl(32 - (idx &&& 31)))

    member this.Numbits() = 32

    member this.Signbit() = 1 <<< (this.Numbits() - 1)

    member this.Item with get idx = (this.Lsr(idx)) &&& 1

​

    member this.GetSlice(start, finish) =

        let start = defaultArg start 0

        let finish = defaultArg finish 31

        let mask = ~~~ (0xffffffff.Lsl(finish + 1))

        (this &&& mask).Lsr(start)

​

    member this.SetSlice(start, finish, value:int) =

        let start = defaultArg start 0

        let finish = defaultArg finish 31

        let mask = ((1 <<< (finish + 1 - start)) - 1) <<< start

        (this &&& ~~~ mask) ||| value.Lsl(start)

​

​

let a = 0x1234

let b = a.[8..15] <- 0x67

let c = b.[4..11]

printfn "%x" a

printfn "%x" b

printfn "%x" c

​