F# Trace

Trace.fs

open System
open System.Diagnostics
open System.Runtime.CompilerServices
open System.Runtime.InteropServices

let activitySource = new ActivitySource("Test")

[<IsReadOnly; Struct>]
type Trace<'T>(activitySource: ActivitySource) =
    static let typeName = typeof<'T>.Name

    member _.Test([<CallerMemberName; Optional; DefaultParameterValue("_")>] callerName: string) =
        printfn $"{typeName}.{callerName}"

    member _.Span([<CallerMemberName; Optional; DefaultParameterValue("_")>] callerName: string) =
        if activitySource.HasListeners() then
            activitySource.StartActivity($"{typeName}.{callerName}")
        else
            null

[<AutoOpen>]
module Tracing =
    let trace<'T>() = Trace<'T>(activitySource)

type Foo() =
    static let trace = trace<Foo>()

    member this.Bar() =
        use _ = trace.Span()
        trace.Test()

Foo().Bar()