I'm not trying to be insulting, but did you read the article? From what you've written, it sounds like you haven't actually used an expressive type system. For

I'm not trying to be insulting, but did you read the article? From what you've written, it sounds like you haven't actually used an expressive type system. For instance, in Haskell I can type 2 + 3.75 and I get 5.75 right back -- no errors. That's because the type signature of + is "Num a => a -> a -> a," meaning I can add two of any type of Number (Integers and Floats are both Numbers, of course).