"One important thing to note though, is that I honestly don’t think this will work well, unless the language has at least type inference and support for ADTs"

"One important thing to note though, is that I honestly don’t think this will work well, unless the language has at least type inference and support for ADTs" I think this is spot on. That was my journey as well. I started using Python in around 2000 because I didn't had to write type of every local variable and declare every little structure. (For example, you want to return multiple values in a tuple? Better declare it as structure or object.) For a long time, Python was my favorite language. Eventually, I came to Haskell and it became a new favorite. I think the "hype" of the dynamic languages subsided largely because of the two important developments you mentioned (which are now in some form a standard in any new language that is being developed).