[m-users.] Reading the entire directory contents (contribution for the posix library)

[Volker Wysk]

Am Montag, den 14.10.2019, 13:57 +1100 schrieb Julien Fischer:
> 
> On Mon, 14 Oct 2019, Zoltan Somogyi wrote:
> 
> > On Mon, 14 Oct 2019 13:37:51 +1100 (AEDT), Julien Fischer <
> > jfischer at opturion.com> wrote:
> > > > Maybe dir_contents should be added to the "dir" library?
> > > 
> > > I'm not convinced that it is generally useful enough to warrant
> > > inclusion it the standard library.
> > 
> > I think it is useful enough.
> 
> I disagree, returning the directory contents in a particular order
> seems quite application specific.  Why just return their names?
> In many circumstances you would presuambly be interested in what
> kind of file each entry is as well.
> 
> OTOH, if others feel strongly that this is something that should
> be in the stdlib, then I suggest the following:
> 
>        % contents(DirName, Result, !IO):
>        % Return the entries of the directory DirName sorted according
>        % to the standard order for strings.
>        %
>     :- pred contents(string::in,
>        io.maybe_partial_result(list(string))::out, io::di, io::uo)
>        is det.
> 
>        % contents(CmpPred, DirName, Result, !IO):
>        % Return the entries of the directoryDirName sorted according
>        % to CmpPred.
>        %
>     :- pred contents(comparison_pred(string)::in(comparison_pred)
>          string::in, io.maybe_partial_result(list(string))::out,
>          io::di, io::uo) is det.

This still introduces complexity (less, but still), which won't be
needed most of the time.

I suggest adding a front end to your contents() predicates, which is
just:

:- pred contents(string::in, list(string)::out, io::di, io::uo).

Cheers,
Volker