FWIW, most quickie syntactic sugar extensions that are confined to single lines of code work seamlessly with twt. I use pa_compr all the time, for example. I think open_in and try...finally are currently problematic, but if they do become some kind of de facto standard then I would have no problem hacking them into this already-badly-hacked preprocessor. In the future, someone needs to do twt right; it works well enough for me right now that I have no motivation to do so.

 

-Mike