[domlebo70]

To OP: You could avoid the visitor by using an IIFE style switch using the run utility fn:

    export const run = <T>(f: () => T): T => f();

Now you can go:

    const inferred_type = run(() => {
      switch(blah) {
        ...
      }
    })

[mgreenw]

Exactly! I wrote a post about this pattern: https://maxgreenwald.me/blog/do-more-with-run

[domlebo70]

Yeah this is where I heard about it :P I showed all my dev friends, and our minds were equally blown away by the obviousness of it.

[gavinray]

You don't even need to do this much, you can just invoke the function and let the return type be inferred.

  const inferred = (() => "Hello")() // Inferred as "string"

If you really don't want to use an IIFE because you don't like the "()" at the end, you can just:

  const myFn = () => { switch(...) }
  const inferred = myFn()