Elixir Message Passing

message_passing.ex

## Kernel.send/2 function
send(pid, { :an, :arbitary, :term } )

receive do 
pattern_1 -> do_something
pattern_2 -> do_something_else

## Example to be executed in IEX 
send(self, "a message")

"a message"
receive do 
  message -> IO.inspect message
end

## if a receive block runs, and the mailbox is empty, the receive block runs indefinately.
receive do 
  message -> IO.inspect message
  after 5000 -> IO.puts "message not received"
end

run_query = fn(query_def) -> 
  :timer.sleep(2000)
  "#{query_def} result"
end

## async_query with message passing 
## sending processes
async_query = fn(query_def) ->
  caller = self
  spawn(fn ->
    send( caller, {:query_result, run_query.(query_def)})
  end)
end

Enum.each(1..5, &async_query.("query #{&1}"))

# result is stored in the mailbox of the caller process