A version of Add-Type for F# in PowerShell

AddFSharpType.fs

namespace AddFSharpType

module AddFSharpType =
  open System.IO
  open FSharp.Compiler.CodeAnalysis
  open System
  /// This is basically the compiler so we name it that way
  let compiler = FSharpChecker.Create()

  let AddFromFile (sourceFile : string) =
    let destination = "ThisIsIgnoredForDynamicAssemblyCompliation.dll"
    let initializeOpts = Some(stderr, stdout)
    let errors, exitCode, assembly =
      compiler.CompileToDynamicAssembly([|
        "fsc.dll"
        "--noframework"
        "-a"; sourceFile
        "-o"; destination
        "-I"; "C:/Users/JGrote/Projects/FSharp/out"
        "-I"; "C:/Program Files/dotnet/sdk/6.0.100-rc.2.21505.57/Microsoft/Microsoft.NET.Build.Extensions/net461/lib"
      |], initializeOpts)
      |> Async.RunSynchronously
    // TODO: Better error handling
    if exitCode > 0 then raise (InvalidOperationException(errors.[0].ToString()))
    assembly.Value

  let AddType (typeDefinition : string) =
    let tempName = Path.GetTempFileName()
    let tempFile = Path.ChangeExtension(tempName, ".fsx")
    File.WriteAllText(tempFile, typeDefinition)
    AddFromFile(tempFile)

/// The PowerShell Cmdlet to implement the above
open System.Management.Automation
[<Cmdlet("Add", "FSharpType")>]
type AddFSharpTypeCommand () =
  inherit PSCmdlet ()
  [<Parameter>]
  member val TypeDefinition : string = "" with get, set

  override this.EndProcessing() =
    let assembly = AddFSharpType.AddType(this.TypeDefinition)
    this.WriteObject(assembly)
    base.EndProcessing()