choose

open BenchmarkDotNet.Running
open BenchmarkDotNet.Attributes
open BenchmarkDotNet.Configs
open BenchmarkDotNet.Diagnostics.Windows

let rec chooseAllAcc f xs acc =
    match xs with 
    | [] -> List.rev acc
    | h :: t -> 
            match f h with 
            | None -> chooseAllAcc f t acc 
            | Some x -> chooseAllAcc f t (x::acc)

let chooseOriginal f xs = chooseAllAcc f xs []

type choose () =
    [<Params(10, 100, 10000, 1000000)>] 
    member val public count = 0 with get, set

    [<Benchmark>]
    member this.choose () =
        List.choose (fun i -> if i%2 = 0 then Some i else None) [1..this.count]

    [<Benchmark>]
    member this.chooseOriginal () =
        chooseOriginal (fun i -> if i%2 = 0 then Some i else None) [1..this.count]

let [<EntryPoint>] main args =
    let config = ManualConfig.Create(DefaultConfig.Instance)
    config.Add(new MemoryDiagnoser())
    config.Add(new InliningDiagnoser())
    BenchmarkRunner.Run<choose>(config) |> ignore
    0