Records lose information in type constructors

[j14159]

Consider the following:

type t = T {x: int}

let make_t_with_xy = T {x=1, y=2}

let main () =
  let example_t = make_t_with_xy in
  match example_t with
    T rec -> rec  -- rec loses y: int

This information loss occurs because type constructors don't carry any information about their arguments - they're used only to make type arrows that instantiate their parent type. This means that even though T {x=1, y=2} keeps the y: int in its row variable, going from T rec has no access to it. I think there are a couple of possibilities to solve this:

• package type information with type constructors. How this gets propagated to the type might get really messy.
• synthesize ADT type variables for the row variable in each record that exists in an ADT.

I think the latter is somewhat tractable but the larger question I have is: should we bother? Is preserving this information desirable? I suspect it is purely for consistency's sake but am curious as to others' opinions.