learning Erlang

afile_client.erl

-module(afile_client).
-export([ls/1, get_file/2, put_file/3]).

ls(Server) ->
  Server ! {self(), list_dir},
  receive
    {Server, FileList} -> 
      FileList
  end.

get_file(Server, File) ->
  Server ! {self(), {get_file, File}},
  receive
    {Server, Content} ->
      Content
  end.

put_file(Server, FileName, Content) ->
  Server ! {self(), {put_file, FileName, Content}},
  receive
    {Server, X} ->
      X
  end.


% c(afile_client).
% c(afile_server).
% Server = afile_server:start(".").
% afile_client:put_file(Server, "hello.txt", "hello world").

afile_server.erl

-module(afile_server).
-export([start/1, loop/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)};

    {Client, {put_file, FileName, Content}} ->
      Full = filename:join(Dir, FileName),
      Client ! {self(), file:write_file(Full, Content)}
  end,
  loop(Dir).