This library provides a bounded first-in first-out channel type for use in
STM. It supports a limit on the total size of items in the channel.
stm-sbchan also provides a few features not found in other bounded channel
libraries, such as:
Alternative overflow strategies cramSBChan and rollSBChan.
cramSBChan ignores the channel's size limit, and rollSBChan
removes old items from the beginning of the channel when it fills up.
The channel limit can be adjusted at runtime.