Streams for Communication

stream: an indefinitely expanding list of messages
good foundation for modeling the ever extended sequence of messages received by an agent

using logic variables: a list whose tail is a variable

declare L0                  %% L0 = _
declare L1 in L0=a|L1       %% L0 = a|_
declare L2 in L1=b|L2       %% L0 = a|b|_
declare L3 in L2=c|L3       %% L0 = a|b|c|_