[erlang-questions] Issue with "Programming Erlang" sample

John Williston <>
Tue Apr 16 14:52:11 CEST 2013


Good morning,

 

I'm learning Erlang using the Programming Erlang (2d ed) text from
Pragmatic Bookshelf. Chapter two, "A Whirlwind Tour of Erlang" includes
a file server sample that's failing to work as the book suggests, and
I'm afraid I'm not getting anywhere figuring it out. First, here's the
server code:

 

-module(afile_server).

-export([start/1]).

 

start(Dir) -> spawn(afile_server, loop, [Dir]).

 

loop(Dir) ->

    receive

        {Client, list_dir} ->

            Client ! {self(), file:list_dir(Dir)};

        {Client, {get_file, File}} ->

            Full = filename:join(Dir, File),

            Client ! {self(), file:read_file(Full)}

    end,

    loop(Dir).

 

That compiles (albeit with a warning saying "Warning: function loop/1 is
unused") but when I try to execute it from within the shell I get an
error. For sake of reference the shell commands I'm issuing are:

 

Eshell V5.10.1  (abort with ^G)

1> c(afile_server).

afile_server.erl:7: Warning: function loop/1 is unused

{ok,afile_server}

2> FileServer = afile_server:start(".").

<0.39.0>

3>

=ERROR REPORT==== 10-Apr-2013::10:31:17 ===

Error in process <0.39.0> with exit value:
{undef,[{afile_server,loop,["."],[]}]}

 

Can anyone suggest what might be wrong? I'm running under Windows 7
Professional x64 for sake of reference. Thanks in advance!

 

John

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