Here’s the Typed Racket file I came up with today https://gist.github.com/DanBurton/f0a1472daa8bfdeb21fbbaca783a943c I found the Clojure macros some->> and when-let to be surprisingly nice to use with Typed Racket, since they expand into and forms that TR can inspect and leverage to propagate type refinements. I invented a simple macro, guard, to complement some->> for when I wanted to specify a particular type refinement.

I also ended up using call-with-composable-continuation, which I do not pretend to understand at all, but it had the right type when call/cc for some reason didn’t. (The type didn’t support passing the prompt tag as its 2nd arg.)