Реализация тестового задания на примере https://github.com/podkolzzzin/Stream.Profiling

stupid_file_sort_in_fsharp.fsx

open System
open System.IO

let num () = Random.Shared.Next(0, 10_000)

let alf =
    [| ' ' |]
    |> Array.append [| 'A' .. 'Z' |]
    |> Array.append [| 'a' .. 'z' |]

let str () =
    String(
        [| for i = 0 to Random.Shared.Next(20, 100) do
               yield alf.[Random.Shared.Next(0, alf.Length)] |]
    )

let gen count =
    Seq.init count (fun i -> $"{num ()}.{str ()}")

let count = 2_000_000

Directory.SetCurrentDirectory(@"c:\\tmp\\tests\\1")
let source = $"L{count}.txt"
let dist = $"S{count}.txt"

let do_it () =
    File.WriteAllLines(source, gen count)

    File.ReadAllLines(source)
    |> Seq.sortWith (fun s1 s2 ->
        let p1 = s1.IndexOf('.')

        let v1 = s1.AsSpan(p1 + 2)
        let p2 = s2.IndexOf('.')

        let v2 = s2.AsSpan(p2 + 2)

        let vc =
            v1.CompareTo(v2, StringComparison.Ordinal)

        if not (vc = 0) then
            vc
        else
            let n1 = Int32.Parse(s1.AsSpan(0, p1))
            let n2 = Int32.Parse(s2.AsSpan(0, p2))
            n1.CompareTo(n2))
    |> fun result -> File.WriteAllLines(dist, result)

#time
do_it ()

(*

C:\tmp\tests\Stream.Profiling\Stream.Profiling>dotnet run                                      
Execution took: 00:00:57.0215479            

C:\tmp\tests\1>dotnet fsi --exec sortfile.fsx     
Real: 00:00:13.280, ЦП: 00:00:13.687, GC gen0: 2051, gen1: 23, gen2: 3 

WOW! In 4.4 faster! I am shocked!
*)