Erlang中的匹配模式总结

消息传递匹配

loop() ->
    receive
        {From, {rectangle, Width, Height}} ->
            From ! {self(), Width * Height},
            loop();
        {From, {circle, R}} ->
            From ! {self(), 3.14 * R * R},
            loop();
        {From, _Other} ->
            From ! {self(), {error, unknown_shape}}
            loop()
    end.
Pid = spawn(fun loop/0).
Pid ! {self(), {rectangle, 10, 5}}.         % {Pid, 50}
Pid ! {self(), {circle, 4}}.                % {Pid, 50.24}
Pid ! {self(), {square, 10}}.               % {Pid, {error, unknown_shape}}