I think you missed my point that what you're describing as the "old" idea were actually the "new" idea with a corresponding "old" idea. For instance, you mentio

I think you missed my point that what you're describing as the "old" idea were actually the "new" idea with a corresponding "old" idea. For instance, you mention OCaml's typing, but OCaml is from 1996 and Milner's type-inference work (which was for an early version of ML) is from 1982. And ML itself is from 1973 according to https://en.wikipedia.org/wiki/ML_(programming_language) https://en.wikipedia.org/wiki/ML_(programming_language) ... [My personal experience from doing related-work searches for research papers is that there was often an at least somewhat relevant reference from the 60s...]