Basic Ideas (1): Linear Channels
c : pm ? chan
p (polarity) ::= ? (output) | ? (input) | ? (both) | ? (none)
¡ÈIn which direction c can be used¡É
m (multiplicity) ::= 1 (exactly once) | ? (any times)
¡ÈHow many times c can be used¡É
c:?1 int chan¨§ send(c, 3):unit
c:?1 int chan¨§ recv(c):int