> Also I think the name 'sum type' is bad. The intuition is that for each types A and B with number of elemnts |A| and |B| the sum type A+B has number of eleme

> Also I think the name 'sum type' is bad. The intuition is that for each types A and B with number of elemnts |A| and |B| the sum type A+B has number of elements |A|+|B|.