Trouble toggling or not toggling a default function. (How do I do something like Python's `__name__ == "__main__"`?)

main=name.fsx

#if INTERACTIVE

let args = fsi.CommandLineArgs
if args.[0].Contains("Seq2.fsx") then
   // works when run with fsharpi as one bash command
   // 
   // Usage A:
   //    $ fsharpi Seq2.fsx
   main (args.[1..])
else
   // works when loaded and opened in fsi
   //
   // Usage B:
   //    $ fsharpi
   //    > #load "Seq2.fsx";;
   //    > open Seq2;;
   printfn "« not running Seq2 main »"
   0

#else
#if MAIN_SEQ2

// works when built with a custom symbol for these compiler directives
//
// Usage C:
//    $ fsharpc --define:MAIN_SEQ2 --target:exe Seq2.fsx
//    $ mono Seq2.exe
[<EntryPoint; STAThread>]
let demo args =
   // although here we also have access
   // to System.Environment.GetCommandLineArgs(),
   // which also has item 0, too (unlike entrypoint args)
   main args

#else

// Usage D:
//    $ fsharpc --target:exe OtherThing.fsx
//    $ mono OtherThing.exe

#endif
#endif

Well, I suppose I can define a symbol to test with compiler directives like MAIN_SEQ2 and get by, but there's gotta be a more elegant way.