The following procedures are said to return an unspecified value,
but that makes them useless because they are not required to have
any side effects:

    list-sort!
    list-stable-sort!
    list-merge!  (see note below)
    vector-merge

The current draft's specification of list-merge! ends by saying:

    It returns the deduplicated input. It returns an unspecified value.

The specification of vector-select! is missing an ordering predicate.
It is also said to run "in O(k) time", which is impossible because it
must examine start-end elements, which is arbitrarily larger than k.

There are also several bugs in the reference implementation, but
I'll be reporting those in a separate email.

Will