Hi.

Seems to be a useful draft, thanks.

One remark about queue-length:
as queues are much more restricted than lists, it would
be easy to store (and update) the queue-length in the underlying
representation of the queue.
This would change O(n) (for queue-length) into O(1).
If you imagine large queues, O(n) could make this SRFI unattractive
or impractical.

Ciao
Sven