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

Zsolt Czinkos <>
Tue Apr 16 15:07:24 CEST 2013


Hi,

You should export loop function, too.

-export([start/1, loop/1]).

Best,

Zsolt

On Tue, Apr 16, 2013 at 2:52 PM, John Williston <>wrote:

> 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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> 
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>
>
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