I don't know if it is theoretically sound or possible, but

it would be helpful, if the typing of match-with statements with polymorphic

variants was able to remove one or more variants from the "catch-all" cases

In the following code, it would mean that three_is_a_lot would be typed like

three_is_a_lot_2 without having to write all the cases.

# let how_much = function

| 1 -> `One

| 2 -> `Two

| 3 -> `Three

| n -> `A_lot;;

val how_much : int -> [> `A_lot | `One | `Three | `Two ] = <fun>

# let three_is_a_lot x =

match how_much x with

| `Three -> `A_lot

| any -> any;;

val three_is_a_lot : int -> [> `A_lot | `One | `Three | `Two ] = <fun>

# let three_is_a_lot_2 x =

match how_much x with

| `Three -> `A_lot

| `One | `Two | `A_lot as any -> any;;

val three_is_a_lot_2 : int -> [> `A_lot | `One | `Two ] = <fun>