Refined polyvariants are not accepted

[TomiS]

Howdy. So the title is probably a bit unclear, but here's an example.

I'm trying to create a theme object with a field pageWidth that uses Bs-css atomic types. If I type it like below, it works nicely when used together with e.g. width function styles([width(theme##pageWidth)]).

// This works
type theme = {
  .
  "pageWidth": [
    Types.Width.t
    | Types.Percentage.t
    | Types.Length.t
    | Types.Cascading.t
  ],
};

However, if I'd like to be more specific and always require the width in millimeteres, it doesn't work.

// This doesn't work even if it should, imho
type theme = {
  .
  "pageWidth": [ | `mm(float) ]
};

The problem is probably related to upper boundaries missing somewhere. A simplified example of a similar situation here:
https://reasonml.github.io/en/try?rrjsx=true&reason=C4TwDgpgBANhB2BzYALKBeKBtKAfKABgLZEAUAZjAPYCGwAlHoWAB6kCW8DTBYwF1OowC6AKFFxgUAO7sAJqgxRSMAFzYAPLATIUwxugB8sANxQA9ACooASSjwIEOVGBUoNOc4IaCUclQAnFxR2AGcXN2lAgGsAQihLcwkIKRQIdkQUKUwVdTgkVANjGDMrKABRFhoiMDgoKnIoAGMAVwCAhCkAIwgUGgA3dkCEpOSpEnUcfGIySlpuYSUZ0gBmAAYAOjX6E3FZBRRSEh2LayiA6PDE0TSMrKOiE7K5Kghw+Copc+ioUPYidgwGgBGAgCJQFBUaRQLqhAC0TVC4Si8AA5F8YiMgA

I tried to look into actually fixing this, but the bindings were complex enough so that I didn't immediately figure it out.

I encountered the issue in width function when trying to use mm(float) polyvariant.

[TomiS]

Actually, could it be as simple as that? ^

Of course, all other functions would need similar treatment too.