main.erl

-module(main).

-export([run/0, hold/0, example/0]).

hold() ->
    receive
        % ...
    after
        1000 ->
            io:format("Timed out: ~p~n", [self()])
    end.

run() ->
    % First, lets spawn a thing to do something 1 second after
    % its invocation.
    HoldPid = spawn(main, hold, []),

    % Which process are we waiting for?
    io:format("Holding process: ~p~n", [HoldPid]),

    % Now, lay down a log entry if we can.
    case file:open("log", [append]) of
        {error, Reason} ->
            io:format("Could not open log file: ~p~n", [Reason]);
        {ok, Fd} ->
            io:format("Opened file.~n"),

            % Got our file handle. Now to write something!
            file:write(Fd, <<"Some bytes. Represented as a string.">>),
            file:write(Fd, <<"\n">>),
            file:close(Fd)
    end.

% 32768 16348 8192 4096 2048 1024 512 256
%     0     0    0    0    0    0   0   0
%   128    64   32   16    8    4   2   1
%     0     0    0    0    0    0   0   0
%
% <<A:16, B/binary>> = <<1, 2, 3, 4>>.
%
% A = 258
% B = <<3, 4>>
%
% How did we arrive at 258?
%
% A == 258 because we've placed the bit
% signature of the number "1" into the higher
% range of our 16-bit sequence. Therefore it
% actually represents the value "256".
%
% This would be a logical left-shift of 8 bits.
%
% As the number "2" now falls into the lower
% range of bits, it is not shifted, simply
% applied.
%
% The resulting integer value is 258.
example() ->
    Bin = <<1,2,3,4>>,

    % Examine our raw bytes.
    io:format("Before operations: ~p~n", [Bin]), % <<1,2,3,4>>

    % Now, take 2 of those bytes (16 bits) and
    % shift them into an integer. Allow the rest
    % to fill up our second value.
    <<A:16, B/binary>> = Bin,

    % We should now have an integer and our
    % remainder: 
    io:format("Our integer: ~p~n", [A]), % 258
    io:format("Our remainder: ~p~n", [B]). % <<3,4>>

% Unused. Some no-ops.
connect() ->
    % Connect to various nodes. Say, that we've scanned
    % out of a config.
    net_kernel:connect_node(testing0@jajohnson),
    net_kernel:connect_node(testing1@jajohnson),

    % Spawn a process on another node.
    spawn(testing1@jajohnson, main, example, []),

    % Our node name and all the nodes we're connected to.
    node(),
    nodes().