CODEWITHSUNDEEP
erlang
Perroquiet
Perroquiet

Reputation: 177

Erlang: Parallel message passing from a List of data to to a List of Processes

How do I implement a simultaneous passing from all values in a List A, to a List of Processes B? Both List A & B are of equal size. Let's say A = [1,2,3] and B = [<0.42.0>,<0.43.0>,<0.44.0>]. I want to pass the value 1 to process <0.42.0> and so on in parallel execution.

Here is what I came up so far:

pass_values([P|ValueListA], [H|ProcessListB]) ->
    H ! {foo, P},
    pass_values(ValueListA, ProcessListB).

Upvotes: 0

Views: 253

Answers (1)

Ning
Ning

Reputation: 2880

What you are looking for is a scatter utility that takes an array of elements and distributes the elements to an array of processes.

-module(lab).

-compile(export_all).

go() ->
    ProcessList =
        lists:map(fun(_) ->
                          spawn(?MODULE, echo, [])
                  end,
                  lists:seq(1, 6)),
    DataList = ["E", "r", "l", "a", "n", "g"],
    scatter(DataList, ProcessList).

scatter(DataList, ProcessList) ->
    lists:foreach(fun({Data, Process}) ->
                          Process ! Data
                  end,
                  lists:zip(DataList, ProcessList)).

echo() ->
    receive
        Msg ->
            io:format("~p echos ~p~n", [self(), Msg]),
            echo()
    end.

Give it a try:

1> c(lab).
{ok,lab}
2> lab:go().
<0.40.0> echos "E"
<0.41.0> echos "r"
<0.42.0> echos "l"
<0.43.0> echos "a"
<0.44.0> echos "n"
<0.45.0> echos "g"
ok

Upvotes: 1

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