So, that covers the main ideas from Haskell 98’s type system. Let’s evaluate it.
I described the design of type systems (and programming languages) as a balancing act: you want the articulacy (freedom to say interesting things) but want to retain some useful automation, ease of use, and conceptual consistency. It is very rare to get both.
Haskell manages a pretty good balance, though, I believe. The type system is pretty versatile, and only requires explicit hints when you’re using complex overloading. What can’t Haskell do, or do nicely?
Well, most of the things I’ll cover soon under dependent types! But there are some aspects of traditional OOP that don’t translate nicely, primarily the ability to build lists ...