This was the most infuriating part. He either doesn't understand what a hof is, is actively lying, or just hasn't even used typescript long enough to understand this is incorrect.

Please show me the proper typing of the map transducer in TypeScript. I'm willing to learn.

It would seem that someone's done it already: https://github.com/DefinitelyTyped/DefinitelyTyped/blob/mast...

Yeah, I use both all the time.

I will admit I have to pass type hints via generics to my compose / pipe calls more often than I would like, but it definitely still works.