I'm not sure if it's what you're looking for, but algebraic days types are a fairly common way to encode different kinds of days that have the same shape. You

I'm not sure if it's what you're looking for, but algebraic days types are a fairly common way to encode different kinds of days that have the same shape. You may also be looking for fields: https://en.m.wikipedia.org/wiki/Field_(mathematics) https://en.m.wikipedia.org/wiki/Field_(mathematics). You could probably also describe the relation between different number types as linear operators over a vector space