PROPOSAL: Add 'Natural' type to base:Data.Word

[Andres Löh]

Hi.

> I hereby suggest to add a type for encoding term-level naturals
>
>   data Natural = <opaque/hidden>
>        deriving (...the usual standard classes...)

+1 in general

FWIW, I'm in favour of:

* not putting this into Data.Word, but rather into Data.Nat or Data.Natural
* having default subtraction to be saturated rather than partial
* adding a Nat type for bounded naturals as well (even if it's just a
synonym for Word)

Cheers,
  Andres