Computes hash ids for objects such that two objects that are =-equal have the same hash id. This function is similar to equal-hash, but does not involve physical addresses, thus making this a suitable hash function for subclasses of <value-table>.
open
| thing | An instance of <object>. |
| initial-state | An instance of <hash-state>. |
| hash-id | An instance of <integer>. |
| hash-state | An instance of <false>. |