5360c.fs

open System
open System.Diagnostics

let getNextRandom () =
    let r = Random ()
    let rec getNext m =
        match r.Next () with
        | n when m |> Map.containsKey n -> getNext m
        | n -> n
    getNext

let getNextSequential () =
    let mutable idx = 0
    let rec getNext _ = 
        idx <- idx + 1
        idx
    getNext

let validate l m =
    l |> List.iter (fun (k,v) -> 
        let check = m |> Map.find k
        if check <> v then failwith "boom")

let test getNextKey iterations =
    let r = Random ()
    let rec loop idx l m =
        if idx = iterations then ()
        else
            let key = getNextKey m
            let m = m |> Map.add key idx
            validate l m
            loop (idx+1) ((key,idx)::l) m
    loop 0 [] Map.empty


[<EntryPoint>]
let main argv =
    let f = 
        match argv with
        | [| "sequential" |] -> getNextSequential ()
        | [| "random" |] -> getNextRandom ()
        | _ -> failwith "invalid arg"

    for i = 1 to 5 do
        let sw = Stopwatch.StartNew ()

        test f 3000

        printfn "%s,%s,%d" argv.[0] (if Environment.Is64BitProcess then "64-bit" else "32-bit") sw.ElapsedMilliseconds

    0