Implements bounded channels. These channels differ from normal
that they are guaranteed to contain no more than a certain number of
elements. This is ideal when you may be writing to a channel faster than you
are able to read from it.
This module supports all the functions of Control.Concurrent.Chan except
dupChan, which are not supported for bounded channels.
Extra consitency: This version enforces that if thread Alice writes e1 followed by e2 then e1 will be returned by readChan before e2. Conversely, if thead Bob reads e1 followed by e2 then it was true that writeChan e1 preceded writeChan e2.
Previous versions did not enforce this consistency: if writeChan were preempted between putMVars or killThread arrived between putMVars then it can fail. Similarly it might fail if readChan were stopped after putMVar and before the second takeMVar. An unlucky pattern of several such deaths might actually break the invariants of the array in an unrecoverable way causing all future reads and writes to block.
newBoundedChan n returns a channel than can contain no more than
Write an element to the channel. If the channel is full, this routine will block until it is able to write. Blockers wait in a fair FIFO queue.
Read an element from the channel. If the channel is empty, this routine will block until it is able to read. Blockers wait in a fair FIFO queue.
DANGER: This may block on an empty channel if there is already a blocked reader.
True if the supplied channel is empty.
Return a lazy list representing the contents of the supplied channel. Competing readers might steal from this list.