binary-trees F# .NET Core #5 program

// The Computer Language Benchmarks Game
// https://salsa.debian.org/benchmarksgame-team/benchmarksgame/
//
// Modification by Don Syme & Jomo Fisher to use a nullable Next element
// Based on F# version by Robert Pickering
// Based on ocaml version by Troestler Christophe & Isaac Gouy
// Multithreaded by Anthony Lloyd

type Next = Next of Tree * Tree
and [<Struct>] Tree = Tree of Next

[<EntryPoint>]
let main args =
    let minDepth = 4
    let maxDepth =if args.Length=0 then 10 else max (minDepth+2) (int args.[0])
    let stretchDepth = maxDepth + 1

    let rec make depth =
        if depth=0 then Tree Unchecked.defaultof<_>
        else Next (make (depth-1), make (depth-1)) |> Tree

    let check t =
        let rec tailCheck (Tree n) acc =
            if box n |> isNull then acc
            else
                let (Next(l, r)) = n
                tailCheck l (tailCheck r acc+2)
        tailCheck t 1

    let stretchTreeCheck = System.Threading.Tasks.Task.Run(fun () ->
        let check = make stretchDepth |> check |> string
        "stretch tree of depth "+string stretchDepth+"\t check: "+check )

    let longLivedTree =
        let tree = make maxDepth
        tree, System.Threading.Tasks.Task.Run(fun () ->
            let check = check tree |> string
            "long lived tree of depth "+string maxDepth+"\t check: "+check
        )
    
    let loopTrees = Array.init ((maxDepth-minDepth)/2+1) (fun d ->
        let d = minDepth+d*2
        let n = 1 <<< (maxDepth - d + minDepth)
        let c = Array.Parallel.init System.Environment.ProcessorCount (fun _ ->
                    let mutable c = 0
                    for __ = 1 to n/System.Environment.ProcessorCount do
                        c <- c + (make d |> check)
                    c ) |> Array.sum
        string n+"\t trees of depth "+string d+"\t check: "+string c )

    stretchTreeCheck.Result |> stdout.WriteLine
    loopTrees |> Array.iter stdout.WriteLine
    (snd longLivedTree).Result |> stdout.WriteLine
    0
    

NOTES:
64-bit Ubuntu quad core
.NET Core SDK   3.1.201
Host Version: 3.1.3; Commit: 4a9f85e9f8
<ServerGarbageCollection>true
<ConcurrentGarbageCollection>true


Thu, 07 May 2020 19:40:20 GMT

MAKE:
cp binarytrees.fsharpcore-5.fsharpcore Program.fs
cp Include/fsharpcore/tmp.fsproj .
mkdir obj
cp Include/fsharpcore/project.assets.json ./obj
/usr/bin/dotnet build -c Release --no-restore
Microsoft (R) Build Engine version 16.5.0+d4cbfca49 for .NET Core
Copyright (C) Microsoft Corporation. All rights reserved.

  tmp -> /home/dunham/benchmarksgame_quadcore/binarytrees/tmp/bin/Release/netcoreapp3.1/tmp.dll

Build succeeded.
    0 Warning(s)
    0 Error(s)

Time Elapsed 00:00:11.64

14.28s to complete and log all make actions

COMMAND LINE:
/usr/bin/dotnet ./bin/Release/netcoreapp3.1/tmp.dll 21

PROGRAM OUTPUT:
stretch tree of depth 22	 check: 8388607
2097152	 trees of depth 4	 check: 65011712
524288	 trees of depth 6	 check: 66584576
131072	 trees of depth 8	 check: 66977792
32768	 trees of depth 10	 check: 67076096
8192	 trees of depth 12	 check: 67100672
2048	 trees of depth 14	 check: 67106816
512	 trees of depth 16	 check: 67108352
128	 trees of depth 18	 check: 67108736
32	 trees of depth 20	 check: 67108832
long lived tree of depth 21	 check: 4194303