Editing Haskell in web browser/Basics (section)

====Message passing between threads====

Threads may pass messages to each other, using [http://www.golubovsky.org:5984/_utils/yhcws/Control-Concurrent-JSThreads.html#t%3AMSGBOX   Message Boxes]. Sending messages is asynchronous (although rescheduling of threads execution occurs to resume the receiving thread). Sending a message may fail if there is a message in the ''Message Box'' (no message buffering). Receiving messages is always a blocking operation. Receiving a message may fail if there is already a thread waiting on the ''Message Box''. Therefore more than one thread may send messages to the same ''Message Box'' (but sending all messages is not guaranteed unless result of sending is checked, and appropriate action taken if <code>sendMsg</code> fails), but more than one thread may not receive messages from the same ''Message Box''.