Racket has a very nice built-in debugger in its DrRacket editor, with thread visuals and all. Too bad nobody uses DrRacket, or Racket anymore. Admittedly, even

Racket has a very nice built-in debugger in its DrRacket editor, with thread visuals and all. Too bad nobody uses DrRacket, or Racket anymore. Admittedly, even with the best debugger, finding the cause of runtime errors has always been a pain. Hence everybody's moving towards statically compiled, strongly typed languages.