You will have to educate yourself on Haskell's type system and type category theory in general. The bottom line is that you can be very, very expressive using h

You will have to educate yourself on Haskell's type system and type category theory in general. The bottom line is that you can be very, very expressive using higher level types that simply is not possible in any database at all. Personally I like foreign keys, a lot, and couldnt live without them. I dont think Haskell's type system would be a replacement to that, and would rather use a hybrid of those two.