[erlang-questions] how to make the comprehension work

[Richard A. O'Keefe]

On 18/08/2015, at 5:14 am, Roelof Wobben <r.wobben@REDACTED> wrote:

> Hello,
> 
> I try to extract the modules names from the output of code:loaded_all.
> 
> So I tried this :
> 
> -module(module).
> 
> -export([most_used_function_name/0]).
> 
> most_used_function_name() ->
>   process_module_data(code:all_loaded()).
> 
> process_module_data(Loaded_modules)  ->
>    Module_list = get_modules_name(Loaded_modules).
> 
> get_modules_name(Loaded_Modules_list) ->
>    [ModuleList || [{ModuleList, _}] <- Loaded_Modules_List ].
> 
> 
> 
> but now I see a message that ModuleList is unbound.

Are you *sure* that's the message you got?
It looks to me as if you have
    Loaded_Modules_list        in the arguments
                   ^ lower case "l"
    Loaded_Modules_List        in the body
                   ^ upper case "L"

Also, the elements of code:all_loaded() are tuples (with 2 elements),
NOT lists of tuples, and the first element is a module NAME, not any
kind of module List, so the whole thing reduces to

    [Name || {Name,_} <- code:all_loaded]

2> [Name || {Name,_} <- code:all_loaded()].
[io,erl_distribution,edlin,zlib,error_handler,io_lib,
 prim_eval,filename,erts_internal,unicode,orddict,gb_sets,
 inet_db,inet,ordsets,group,gen,erl_scan,kernel,erl_eval,
 prim_file,ets,lists,sets,inet_udp,io_lib_pretty,code,
 ram_file,dict|...]