August 2015 - cabal-devel

ANN: cabal-install-1.22.6.0 has been released
by Ryan Thomas 27 Jan '16

27 Jan '16

Hi all, A new minor release of cabal-install has been released, this is to pick up a fix for @ezyang's fix for #2502. This is now available on hackage and the downloads page and the sha1sum is listed below. Cheers, ryan d474b0eef6944af1abef92419cea13cee50993f3 cabal-install-1.22.6.0.tar.gz

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Cabal and simultaneous installations of the same package
by Simon Peyton Jones 29 Aug '15

29 Aug '15

Dear Cabal developers You'll probably have seen the thread about the Haskell Platform. Among other things, this point arose: | Another thing we should fix is the (now false) impression that HP gets in | the way of installing other packages and versions due to cabal hell. People mean different things by "cabal hell", but the inability to simultaneously install multiple versions of the same package, compiled against different dependencies is certainly one of them, and I think it is the one that Yitzchak is referring to here. But some time now GHC has allowed multiple versions of the same package (compiled against different dependencies) to be installed simultaneously. So all we need to do is to fix Cabal to allow it too, and thereby kill of a huge class of cabal-hell problems at one blow. But time has passed and it hasn't happened. Is this because I'm misunderstanding? Or because it is harder than I think? Or because there are much bigger problems? Or because there is insufficient effort available? Or what? Unless I'm way off beam, this "multiple installations of the same package" thing has been a huge pain forever, and the solution is within our grasp. What's stopping us grasping it? Simon

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Pull request 2617 (don't require global package database)
by Michael Snoyman 17 Aug '15

17 Aug '15

A few months ago I noticed that pull request 2617[1] implements a change I'd love to see in Cabal: not requiring a global package database for GHCs that support this (7.6 and on). The change is small and self-contained, and looks like a good one to me, but it hasn't been merged. Any chance someone with a commit bit could review? [1] https://github.com/haskell/cabal/pull/2617

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--only-depencies saves time?
by Peder Jakobsen 04 Aug '15

04 Aug '15

I’ve read the Simple Guide to Cabal at http://katychuang.com/cabal-guide/ <http://katychuang.com/cabal-guide/> It says: create a copy of a package by running the command cabal install Some flags can speed up this process --only-dependencies -jN to build N packages in parallel --dry-run to see what cabal plans to do (recommended) But here’s the thing (piping a word count from —dry-run) $ cabal install hakyll --dry-run | wc -l 97 cabal install hakyll --only-dependencies --dry-run | wc -l 96 So it takes 20+ minutes to install a package that you just want to check out for a few minutes, while your CPU melts down in the process? I must be missing something here…? Thanks again for your newbie support, greatly appreciated. P.J.

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Newbie: Can't understand cabal errors during install of hakyll
by Peder Jakobsen 01 Aug '15

01 Aug '15

Hi, Been with Haskell just for few days, and thought it would be a good exercise to run a static site generator to get familiar with various tools, and I’m already running into “cabal hell” I think. :( $ cabal install hakyll Resolving dependencies... cabal: Could not resolve dependencies: trying: hakyll-4.7.2.0 (user goal) next goal: time (dependency of hakyll-4.7.2.0) rejecting: time-1.4.2/installed-d67... (conflict: hakyll => time>=1.5 && <1.6) trying: time-1.5.0.1 trying: process-1.2.0.0/installed-3a4... (dependency of hakyll-4.7.2.0) next goal: unix (dependency of process-1.2.0.0/installed-3a4...) rejecting: unix-2.7.0.1/installed-8ad... (conflict: time==1.5.0.1, unix => time==1.4.2/installed-d67...) rejecting: unix-2.7.1.0, 2.7.0.1, 2.7.0.0, 2.6.0.1, 2.6.0.0, 2.5.1.1, 2.5.1.0, 2.5.0.0, 2.4.2.0, 2.4.1.0, 2.4.0.2, 2.4.0.1, 2.4.0.0, 2.3.2.0, 2.3.1.0, 2.3.0.0, 2.2.0.0, 2.0 (conflict: process => unix==2.7.0.1/installed-8ad...) Backjump limit reached (change with --max-backjumps). I’m running OS X Yosemite 10.2.2 with all the latest versions of Haskell and cabal. Thanks you for listening. :) Peder

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Re: Newbie: Can't understand cabal errors during install of hakyll
by Cyd Parser 01 Aug '15

01 Aug '15

Hi Peder, I'd recommend giving stack a try (https://github.com/commercialhaskell/stack) I have found it easier to use than cabal-install. Many executables will install just fine using `stack install <package-name>`. Packages that stack has trouble creating a build plan for (like hakyll) can usually be installed using the following: stack unpack hakyll cd hakyll-* stack init stack setup stack install `stack install` copies the resulting binaries to ~/.local/bin by default: add that to your path. Cheers, cydparser > Date: Sat, 1 Aug 2015 08:36:55 -0400 > From: Peder Jakobsen <pjakobsen(a)gmail.com> > To: cabal-devel(a)haskell.org > Subject: Newbie: Can't understand cabal errors during install of > hakyll > Message-ID: <D991FCF6-9271-49D9-AEB9-543F8A2F25CC(a)gmail.com> > Content-Type: text/plain; charset="utf-8" > > Hi, > > Been with Haskell just for few days, and thought it would be a good > exercise to run a static site generator to get familiar with various tools, > and I?m already running into ?cabal hell? I think. :( > > > $ cabal install hakyll > Resolving dependencies... > cabal: Could not resolve dependencies: > trying: hakyll-4.7.2.0 (user goal) > next goal: time (dependency of hakyll-4.7.2.0) > rejecting: time-1.4.2/installed-d67... (conflict: hakyll => time>=1.5 && > <1.6) > trying: time-1.5.0.1 > trying: process-1.2.0.0/installed-3a4... (dependency of hakyll-4.7.2.0) > next goal: unix (dependency of process-1.2.0.0/installed-3a4...) > rejecting: unix-2.7.0.1/installed-8ad... (conflict: time==1.5.0.1, unix => > time==1.4.2/installed-d67...) > rejecting: unix-2.7.1.0, 2.7.0.1, 2.7.0.0, 2.6.0.1, 2.6.0.0, 2.5.1.1, > 2.5.1.0, > 2.5.0.0, 2.4.2.0, 2.4.1.0, 2.4.0.2, 2.4.0.1, 2.4.0.0, 2.3.2.0, 2.3.1.0, > 2.3.0.0, 2.2.0.0, 2.0 (conflict: process => unix==2.7.0.1/installed-8ad.. > .) > Backjump limit reached (change with --max-backjumps). > > > I?m running OS X Yosemite 10.2.2 with all the latest versions of Haskell > and cabal. > > Thanks you for listening. :) > > Peder >

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Uninstalling packages?
by Peder Jakobsen 01 Aug '15

01 Aug '15

Hi, just browsed through the user guide on managing packages at at https://www.haskell.org/cabal/users-guide/installing-packages.html <https://www.haskell.org/cabal/users-guide/installing-packages.html> Managing seems to imply that you should also be able to uninstall packages with a simple command. But there seem to be no instructions for how to do this for an installed packaged. What am I missing? Is it called “deregistering”? Thanks again, P.

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