From mboxrd@z Thu Jan 1 00:00:00 1970 From: ludo@gnu.org (Ludovic =?utf-8?Q?Court=C3=A8s?=) Subject: Re: [PATCH 0/2] native-search-paths for GHC Date: Thu, 08 Oct 2015 14:00:47 +0200 Message-ID: <87a8rttvrk.fsf@gnu.org> References: Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Return-path: Received: from eggs.gnu.org ([2001:4830:134:3::10]:50702) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Zk9sW-0003VA-Na for guix-devel@gnu.org; Thu, 08 Oct 2015 08:01:00 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Zk9sV-0000Xc-Tb for guix-devel@gnu.org; Thu, 08 Oct 2015 08:00:56 -0400 In-Reply-To: (Eric Bavier's message of "Wed, 07 Oct 2015 16:27:11 -0500") List-Id: "Development of GNU Guix and the GNU System distribution." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: guix-devel-bounces+gcggd-guix-devel=m.gmane.org@gnu.org Sender: guix-devel-bounces+gcggd-guix-devel=m.gmane.org@gnu.org To: Eric Bavier Cc: Guix-devel , federico.beffa@gmail.com, Federico Beffa Eric Bavier skribis: > On 2015-10-07 11:07, Federico Beffa wrote: [...] >> * If I understand correctly, the configuration files of dependencies >> are >> copied in a unique directory for each package. Instead of copying >> would a symlink work? (There are literally thousands of packages on >> Hackage and hopefully Guix will get more of them.) > > I don't know if symlinking is allowed across store directories, though > if it is, that'd be something to try. Yes it=E2=80=99s allowed. That=E2=80=99s what =E2=80=98union-build=E2=80= =99 (the procedure that builds profiles) does. >> * Some Haskell libraries have a rather large list of dependencies. For >> this reason I can imagine that in some situations GHC_PACKAGE_PATH >> could grow rather long. > > Not every package would end up with an entry in GHC_PACKAGE_PATH, only > those that are installed, or declared inputs. Dependent libraries > would be found when GHC examines the package databases of those > packages. > >> This thought made me wonder if there is a >> maximum length to the value of environment variables that we could >> possibly hit. > > We've already pushed this quite far. E.g. the hydra package creates a > rather sizable PER5LIB path. Nice. :-) AFAIK there=E2=80=99s no limit on the size of an environment variable=E2=80= =99s value. However, it=E2=80=99s a good idea to keep search paths small, to reduce the number of =E2=80=98stat=E2=80=99 calls that have to be done before a given = file is found. Using a symlink forest is a good way to achieve that. Thanks, Ludo=E2=80=99.