[ossopite]

I suppose by enumerations you mean sum types. I would argue that these are pretty fundamental? you have product types (structs/records/tuples) - a value is made up of x and y - and sum types - a value can be either X or Y. I think the combination of these is what you need to precisely express any concrete data type.

[swatson741]

I did mean sum types, variants, etc. It's not really clear what I meant by representing the data but I'm referring to type inference. SML can't solve the problem, and Lisp doesn't have it.