CODEWITHSUNDEEP
erlang
user2445271
user2445271

Reputation: 21

Looking for explanation of Erlang code book

Can someone please explain this line by line?

Many many thanks.

run() ->
        Pid = spawn(fun ping/0),
        Pid ! self(),
        receive
                pong -> ok
        end.
ping() ->
        receive
                From -> From ! pong
        end.

Upvotes: 1

Views: 140

Answers (1)

Hynek -Pichi- Vychodil
Hynek -Pichi- Vychodil

Reputation: 26121

Line by line:

run() ->

Declare the function run/0

    Pid = spawn(fun ping/0),

Spawns new process with initialization function ping/0 and store its pid to variable Pid

    Pid ! self(),

Sends message containing the pid of current process (result of self/0 call) to the process which pid is stored in variable Pid

    receive

Waits for a message (or amount of time if there is after clause)

        pong -> ok

If there is a received message pong, return value ok

    end.

End of receive clause and dot also means there is end of function run/0

ping() ->

Declares the function ping/0

    receive

Waits for a message ...

        From -> From ! pong

When receiving anything, store it in variable From and then send message pong to the process determined by value in From (pid of process executing run/0 function in this case)

    end.

End of receive and also ping/0 function

Upvotes: 6

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