WIP: Redefine for/first and for*/first.

[scolobb]

My very drafty approach at updating the typed definition of typed for/first and for*/first.

I don't currently see any reason why Typed Racket would not be able to contain a proper typed implementation of for/first and for*/first. This PR suggests a very crude and potentially broken approach to implementing these two iterations in Typed Racket. I don't think this PR is mergeable in its current state, but perhaps it may grow into better code.

This discussion contains more details.

[racket-discourse-github-bot]

This pull request has been mentioned on Racket Discussions. There might be relevant details there:

https://racket.discourse.group/t/for-first-for-first-for-and-for-and-for-last-in-typed-racket/1002/4

[capfredf]

you can convert this pr to a draft if you want

[scolobb]

Thank you @capfredf I have just converted this PR to draft.