I have installed Haskell Platform 2012 in Windows 7. I write in the console cabal update and I take a message that there is a new version of cabal. I write cabal install cabal-install . After installation finishes it tells me that the cabal has been installed in C:\username\AppData\Roaming\cabal. So when I do cabal update again I am taking the same message that I have to install the new version of cabal. I have tried to change the cabal directory from the config file but cabal ignores the config file. Is Haskell working only on Unix? Thanks
The problem is that the cabal executable that came with Haskell Platform gets picked up instead of the one that you installed.
You need to edit the value of the PATH environment variable and place %AppData%\cabal\bin before %PROGRAMFILES%\Haskell Platform\...\bin so that it's given higher priority.
You need to add C:\username\AppData\Roaming\cabal (or whatever directory now has the cabal executable -- use e.g. dir or your favorite file manager to verify that you have the right place) to your %PATH% environment variable and restart your command prompt.
The error message is incomplete. Install cabal-install globally as:
cabal install cabal-install --global
Related
Every time I make a new cabal sandbox and run cabal update to get the latest package list, I'm prompted about the availability of a new version of cabal. So I install it in the sandbox using cabal install cabal-install.
I think to myself, I should install this new version globally too, outside of the sandbox. So I leave the sandbox and cabal install cabal-install again.
I expected that this would carry over to the next new sandbox, but it doesn't. Is there any way to make it carry over to save the time of reinstalling it in every new sandbox?
Installing cabal via cabal install cabal-install globally results in a new binary in your home folder in ~/.cabal.
As long as this path is not included in $PATH, the default installed cabal from e.g. /usr/bin will get executed, which will result in the warning of a new available version.
cabal install ghc-mod seems to work, but when I try cabal run ghc-mod I get the following error:
Package has never been configured. Configuring with default flags. If this fails, please configure manually.
cabal: No cabal file found.
Please create a package description file <pkgname>.cabal
The resources I've found seem to suggest that creating a package description file shouldn't be necessary to install a package.
Any ideas?
The standard way to install stuff on Haskell nowadays is within sandboxes.
Go to the terminal and create an empty folder that will house your ghc-mod sandbox. cd into that folder and:
cabal sandbox init
cabal install ghc-mod
After it finishes you will find the ghc-mod binary you seek within .cabal-sandbox/bin. Since it's statically linked it's safe to move it to somewhere in your $PATH.
I strongly encourage you use a sandbox but if you don't want to go to .cabal in your home directory and you will find the binary with bin
I'm a newbie to haskell and cabal, so I'm probably missing something simple.
I updated cabal-install:
sudo cabal install cabal-install
Password:
Resolving dependencies...
Configuring cabal-install-1.22.0.0...
Building cabal-install-1.22.0.0...
Installed cabal-install-1.22.0.0
Updating documentation index
However cabal --version says:
cabal-install version 1.18.0.5
using version 1.18.1.4 of the Cabal library
What happened to cabal-install 1.22.0.0?
There are two ways of making cabal install packages globally. Note that, as a result, cabal may require sudo.
This command will install <PACKAGE> globally:
$ cabal install <PACKAGE> --global
As a more general solution, edit the file ~/.cabal/config and set user-install to False. This will automatically set the --global flag so you can just write cabal install <PACKAGE> without any worry. Here's a snippet of my config file:
...
-- split-objs: False
-- executable-stripping: True
user-install: False
-- package-db:
-- flags:
...
You may also want to set root-cmd to sudo if it's not already, so that cabal will automatically prompt for the root password when it encounters a permission problem.
There's some more info online here.
I see that there's an updated cabal at ~/Library/Haskell/bin, so I could replace /usr/bin/cabal with a symbolic link to this copy or I could copy this binary to /usr/bin.
I'm still interested if there is a more elegant/canonical way to make sure the new cabal is what gets used by default.
TLDR: Try running hash -r
Bash has a PATH hashtable that maps commands to the location of binaries. You may still have an old version of cabal installed somewhere in your PATH (possibly in a sandbox). Since cabal is not a new command, the hashtable will keep serving up the old version. hash -r rebuilds the hashtable, so the shell will correctly find the new version (providing it appears earlier in your path than the old one).
I am using ghc-7.6.3 with cabal-install version 1.18.0.5 using version 1.18.1.3 of the Cabal library. My operating system is Debian Wheezy 7.5.
I have a fresh cabal install, and that I have removed the .ghc from my home directory.
After that I have changed the cabal config file and set:
remote-repo: stackage-nightly-2014-12-15:http://www.stackage.org/snapshot/nightly-2014-12-15
After that I did (following this documentation)
$ cabal update
$ cabal install alex happy yesod-bin
and the build complained that it cannot build package system-filepath-0.4.12.
So, I am trying to build package system-filepath-0.4.12 manually. After unpacking the archive, I cd-ed to the unpacked folder and entered:
$ ghc -o Setup Setup.hs
$ ./Setup configure
which gives:
Configuring system-filepath-0.4.12...
Setup: At least the following dependencies are missing:
text >=0.7.1
But
$ cabal install text
gives:
Resolving dependencies...
All the requested packages are already installed:
text-1.1.1.3
Use --reinstall if you want to reinstall anyway.
How is it possible that a package is reported as installed and missing at the same time?
Should I look for a more stable remote-repo configuration, is there something I can check that might fix the missing text package? Note that I am not using a sandbox.
EDIT
Thanks for pointing out that there are two package databases.
I have now tried both
$ cabal configure
$ cabal build
and
$ Setup configure --user
$ Setup build
Both give no error during configuration, but give the following error during the build phase:
Building system-filepath-0.4.12...
Preprocessing library system-filepath-0.4.12...
/usr/bin/ld: cannot find -lHStext-1.1.1.3-ghc7.8.3
collect2: error: ld returned 1 exit status
Try this instead
cd system-filepath--0.4.12
cabal configure
I am not sure why, but this works for me, whereas Setup.hs gave me the same error (truth be told, I always do it the cabal configure way, and am not sure if your way should also work).
There are (at least) two package databases: a global one available to all users, and a user-specific one. By default, Setup.hs looks in (and installs to) the global one, and cabal-install looks in (and installs to) the user-specific one. You can manually choose one or the other with --user and --global; so, you could fix this either by using
./Setup configure --user
or by
cabal install text --global
You can see the current state of the package databases with ghc-pkg, which will report information about both by default.
I'm trying to set up Haskell from scratch, on Ubuntu 11.04, without using the outdated Debian repository or Haskell-Platform.
I've installed GHC-7.0.4 from source with no problem, and now need to install Cabal (which appears to already be included in GHC in /usr/local/lib/ghc-7.0.4/Cabal-1.10.2.0) and Cabal Install.
The latter specifies several dependencies (parsec and network), each of which has several dependencies of their own (mtl, text, etc).
What's the command to install these packages, that I downloaded from hackage in tar.gz form?
Unpack, then runhaskell doesn't work.
I see Setup.lhs, but it's not clear what that's for or how to use it.
Most of the Haskell documentation I've found assumes you've installed from a repo or Haskell-Package and doesn't really explain this well.
cabal-install has a shell script that does this. If you download it from hackage and install it, you can start bootstrap.sh to install cabal-install. You can then use it to install other packages.
There are two different packages: Cabal and cabal-install. Cabal is a library, and cabal-install is an executable named cabal.
To install a package, cabal-install is an optional convenience wrapper around Cabal, but Cabal is required.
According to http://hackage.haskell.org/trac/ghc/wiki/Commentary/Libraries , Cabal is a 'zero-boot' package, so when you build GHC, Cabal and its dependencies are built for you automatically.
You can use ghc-pkg executable to check which packages are already installed:
# ghc-pkg list
Check if Cabal is in the list after you build GHC. If yes, you can install more packages without cabal-install using this documentation:
http://haskell.org/haskellwiki/Cabal/How_to_install_a_Cabal_package
I suggest you to install cabal-install first, and then install everything else using cabal-install executable. A usual commandine for global installation is this:
# runhaskell Setup configure
# runhaskell Setup build
# sudo runhaskell Setup install
Unpack a package tarball and run the commands in the folder with Setup.hs or Setup.lhs files. Note that a per-user non-root installation is also supported - Use runhaskell Setup configure --user
When you install cabal executable and its dependencies this way, use cabal install {package-name} to install more packages.
Note that Haskell Platform exists mostly because of the pain of installing cabal-install by yourself.