I appreciate the authors argument. On the other hand, isn't the reason there are not more first class data types is that they are so difficult to design general

I appreciate the authors argument. On the other hand, isn't the reason there are not more first class data types is that they are so difficult to design general purpose? Even simple data types vary so much from language to language. It seems reasonable that this is why generalizing more abstract data types don't seem to catch on universally very often. It would be more convincing to see concrete examples, such as a type defined in a language such as Haskell that seems to be more or less universally applicable.