From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark H Weaver Subject: Re: heads-up: Haskell updates Date: Thu, 15 Feb 2018 05:38:59 -0500 Message-ID: <871shmo7uk.fsf@netris.org> References: <87r2ppjbst.fsf@elephly.net> <873723pfya.fsf@netris.org> <871shn8jm5.fsf@elephly.net> <87zi4b744f.fsf@elephly.net> <20180214234721.4e9fe198@scratchpost.org> <87a7waodaa.fsf@netris.org> <87o9kq7gt9.fsf@elephly.net> 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]:54715) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1emGx0-0003xC-SM for guix-devel@gnu.org; Thu, 15 Feb 2018 05:39:39 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1emGww-0002cX-57 for guix-devel@gnu.org; Thu, 15 Feb 2018 05:39:38 -0500 Received: from world.peace.net ([50.252.239.5]:40328) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1emGww-0002cM-1G for guix-devel@gnu.org; Thu, 15 Feb 2018 05:39:34 -0500 In-Reply-To: <87o9kq7gt9.fsf@elephly.net> (Ricardo Wurmus's message of "Thu, 15 Feb 2018 10:17:22 +0100") 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" To: Ricardo Wurmus Cc: guix-devel Ricardo Wurmus writes: > Mark H Weaver writes: > >> I suppose if one reads the error message literally: >> >> Control/Monad/Trans/Resource/Internal.hs:302:10: error: >> =E2=80=A2 Could not deduce (MonadBase IO (Strict.StateT s m)) >> arising from the superclasses of an instance declaration >> from the context: MonadResource m >> bound by the instance declaration >> at Control/Monad/Trans/Resource/Internal.hs:302:10-63 >> =E2=80=A2 In the instance declaration for >> =E2=80=98MonadResource (Strict.StateT s m)=E2=80=99 >> >> "Could not deduce" might be interpreted to include the case where we >> failed for lack of sufficient memory. They might have written the code >> to catch any error at all, including out of memory errors, and report >> the failure with this error message. > > I think that=E2=80=99s a misunderstanding. The cause for the error is ea= rlier > when it complains that some packages depend on different versions of the > =E2=80=9Ctransformers=E2=80=9D package. =E2=80=9CStateT=E2=80=9D is a mo= nad transformer. > > I think that =E2=80=9Cghc-pkg=E2=80=9D fails, which leads to some other v= ersion of the > transformers package (maybe a default included with GHC) to be used. In > the case where ghc-pkg does not fail (as on my laptop) the proper > version is used, so there are no problems finding the expected > instances. Ah, okay, that sounds plausible. I confess that my previous message was somewhat rushed, without much investigation or thought behind it. Apologies for the noise. Regards, Mark