6.1 Sending and Receiving

Without going into the details of channels, we can define a notion of directionality for channels. Suppose we have some channel type chan(bool).

     chan(bool) X;
     chan?(bool) Y;
     chan!(bool) Z;

This declares a channel X with unspecified direction (nondirectional), Y as a read-only (receive-only) directional channel, and Z as a send-only directional channel. Send-only and receive-only channels are the most useful in process port declarations — what use are uni-directional channels in the global or local scopes¹?

• Channel Connections and Directions