F# Debugging in watch mode

README.md

Dotnet watch and debugging

1. run your application with dotnet watch
2. Place waitForDebuggerAttached or waitForDebuggerAttachedAndBreak in your main method and save.
3. App should rebuild printing out pid to attach to
4. Use your debugger (in our case VSCode) to attach to this process. See launch.json for example attach config. See Tutorial: Debug a .NET Core console application using Visual Studio Code
5. You'll have to attach everytime you save, you can try using .NET Auto Attach plugin to alleviate this minor pain.

Idea originally from Krzysztof Cieslak

Debugging.fs

namespace Infrastructure

// search tags: debug, debugger, attach
module Debugging =
  let waitForDebuggerAttached (programName) =
#if DEBUG
    if not(System.Diagnostics.Debugger.IsAttached) then
      printfn "Please attach a debugger for %s, PID: %d" programName (System.Diagnostics.Process.GetCurrentProcess().Id)
    while not(System.Diagnostics.Debugger.IsAttached) do
      System.Threading.Thread.Sleep(100)
#else
    ()
#endif
  let waitForDebuggerAttachedAndBreak (programName) =
#if DEBUG
    waitForDebuggerAttached programName
    System.Diagnostics.Debugger.Break()
#else
    ()
#endif

launch.json

{
    "version": "0.1.0",
    "configurations": [
        {
            "name": ".NET Core Attach to running process",
            "type": "coreclr",
            "request": "attach",
            "processId": "${command:pickProcess}",
            "justMyCode": false,
            "enableStepFiltering": false,
            "symbolOptions": {
                "searchPaths": [
                    "http://srv.symbolsource.org/pdb/Public",
                    "http://srv.symbolsource.org/pdb/MyGet"
                ],
                "searchMicrosoftSymbolServer": true
            },
            "sourceLinkOptions": {
                "*": {
                    "enabled": true
                }
            }
        }
        
    ]
}