Types

Common ancestor type

A common ancestor type is a type computed for a list of types using the following algorithm:

1. Add NONE to the list of types (to make sure the list is never empty).
2. If there is a separate type in the list, add a mark separate in front of all non-separate types in the list.
3. If there is a detachable type in the list, add a mark detachable in front of all attached types in the list.
4. If there is a type in the list to which all other types conform, it is the common ancestor type.
5. Otherwise, add ANY to the list and repeat steps starting from step #2.

Here are some examples: