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Hello World Process Chain
-module(accumulators).
-export([average/1]).
average(X) -> average(X, 0, 0).
average([H|T], Length, Sum) ->
average(T, Length + 1, Sum + H);
average([], Length, Sum) ->
Sum / Length.
Erlang R14B02 (erts-5.8.3) [source] [64-bit] [smp:8:8] [rq:8] [async-threads:0] [hipe] [kernel-poll:false]
Eshell V5.8.3 (abort with ^G)
1> c(accumulators).
{ok,accumulators}
2> accumulators:average([1,10,100]).
37.0
3>
-module(hello_world).
-compile(export_all).
main() ->
HelloPid = spawn(fun() -> hello_node(none) end),
WorldPid = spawn(fun() -> world_node(none) end),
PrintPid = spawn(fun() -> print_node() end),
io:format("Send link messages~n"),
HelloPid ! {next, WorldPid},
WorldPid ! {next, PrintPid},
io:format("Sent messages~n"),
HelloPid ! {message, "I say"},
ok.
hello_node(NextPid) ->
receive
{next, Pid} ->
io:format("Hello Process (~p) linked to ~p~n", [self(), Pid]),
hello_node(Pid);
{message, Message} ->
io:format("Hello Process (~p) receices message (~p)~n", [self(), Message]),
NextPid ! {message, string:concat(Message," Hello")},
hello_node(NextPid);
Message ->
io:format("Hello Process (~p) receives unknown message (~p)~n", [self(), Message])
end,
ok.
world_node(NextPid) ->
receive
{next, Pid} ->
io:format("World Process (~p) linked to ~p~n", [self(), Pid]),
world_node(Pid);
{message, Message} ->
io:format("World Process (~p) receives message (~p)~n", [self(), Message]),
NextPid ! {message, Message ++ World},
world_node(NextPid);
Message ->
io:format("Hello Process (~p) receives unknown message (~p)~n", [self(), Message])
end,
ok.
print_node() ->
receive
{message, Message} ->
io:format("Print Process (~p) receives message (~p)~n", [self(), Message]),
print_node();
Message ->
io:format("Print Process (~p) receives unknown message (~p)~n", [self(), Message])
end,
ok.
-module(hello_world2).
-compile(export_all).
main() ->
HelloPid = spawn(fun() -> hello_node() end),
WorldPid = spawn(fun() -> world_node() end),
PrintPid = spawn(fun() -> print_node() end),
io:format("Send link messages~n"),
HelloPid ! {next, WorldPid},
WorldPid ! {next, PrintPid},
io:format("Sent messages~n"),
HelloPid ! {message, "I say"},
ok.
hello_node() ->
receive
{next, Pid} ->
io:format("Hello Process (~p) linked to ~p~n", [self(), Pid]),
hello_node(Pid);
Message ->
io:format("Hello Process (~p) receives unknown message (~p)~n", [self(), Message]),
hello_node()
end,
ok.
hello_node(NextPid) ->
receive
{message, Message} ->
io:format("Hello Process (~p) receives message (~p)~n", [self(), Message]),
NextPid ! {message, Message ++ " Hello"},
hello_node(NextPid);
Message ->
io:format("Hello Process (~p) receives unknown message (~p)~n", [self(), Message]),
hello_node(NextPid)
end,
ok.
world_node() ->
receive
{next, Pid} ->
io:format("World Process (~p) linked to ~p~n", [self(), Pid]),
world_node(Pid);
Message ->
io:format("Hello Process (~p) receives unknown message (~p)~n", [self(), Message]),
world_node()
end,
ok.
world_node(NextPid) ->
receive
{message, Message} ->
io:format("World Process (~p) receives message (~p)~n", [self(), Message]),
NextPid ! {message, string:concat(Message, " World")},
world_node(NextPid);
Message ->
io:format("Hello Process (~p) receives unknown message (~p)~n", [self(), Message]),
world_node(NextPid)
end,
ok.
print_node() ->
receive
{message, Message} ->
io:format("Print Process (~p) receices message (~p)~n", [self(), Message]),
print_node();
Message ->
io:format("Print Process (~p) receives unknown message (~p)~n", [self(), Message])
end,
ok.
..
25> c(hello_world).
{ok,hello_world}
26> hello_world:main().
Send link messages
Sent messages
Hello Process (<0.140.0>) linked to <0.141.0>
World Process (<0.141.0>) linked to <0.142.0>
Hello Process (<0.140.0>) receices message ("I say")
ok
World Process (<0.141.0>) receices message ("I say Hello")
Print Process (<0.142.0>) receices message ("I say Hello World")
-module(pattern).
-compile(export_all).
%% pattern matching
greet(male, Name) ->
io:format("Hello, Mr. ~s!~n", [Name]);
greet(female, Name) ->
io:format("Hello, Mrs. ~s!~n", [Name]);
greet(_, { FirstName, LastName }) ->
io:format("Hello, ~s ~s!~n", [FirstName,LastName]);
greet(_, Name) ->
io:format("Hello, ~s!~n", [Name]).
%% generic
head([H|_]) -> H.
second([_,X|_]) -> X.
%% bits
rgb(<<Red:8,Green:8,Blue:8>>) ->
{Red, Green, Blue}.
%% guards
old_enough(X) when X >= 16 -> true;
old_enough(_) -> false.
Erlang R14B02 (erts-5.8.3) [source] [64-bit] [smp:8:8] [rq:8] [async-threads:0] [hipe] [kernel-poll:false]
Eshell V5.8.3 (abort with ^G)
1> c(pattern).
{ok,pattern}
2> pattern:greet(male,"Jack").
Hello, Mr. Jack!
ok
3> pattern:greet(female,"Jill").
Hello, Mrs. Jill!
ok
4> pattern:greet(alien,"Paul").
Hello, Paul!
ok
5> pattern:greet(male,{"Tarn", "Barford"}).
** exception error: bad argument
in function io:format/3
called as io:format(<0.25.0>,"Hello, Mr. ~s!~n",[{"Tarn","Barford"}])
6> pattern:greet(whatever,{"Tarn", "Barford"}).
Hello, Tarn Barford!
ok
7> pattern:head([1,2,3]).
1
8> pattern:second([1,2,3]).
2
9> pattern:rgb(<<16#FF00FF:24>>).
{255,0,255}
10> pattern:old_enough(10).
false
11> pattern:old_enough(20).
true
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