You can get it by installing wl-pprint package.

   1  # cabal install wl-pprint

See Also

• http://hackage.haskell.org/cgi-bin/hackage-scripts/package/wl-pprint

Now I am using Haskel and investigating its package system. I found that I can display the list of packages already installed in the environment by typing the command as follows.

   1  ghc-pkg list

And then I want to prepare cabal-install. The tool might be found here

• http://hackage.haskell.org/packages/archive/cabal-install/0.6.2/cabal-install-0.6.2.tar.gz

I had got it and extracted it. After that, I could build the module by this command.

   1  runhaskell Setup.hs configure

At this point, I got error messages like this:

   1  Setup.hs: At least the following dependencies are missing:
   2      Cabal >=1.6&&<1.7,
   3      network >=1&&<3,
   4      HTTP >=4000.0.2&&<4001,
   5      zlib >=0.4&&<0.6

It means I must get them in advance from the HackageDB.

After I got downloaded them all, I must do just runhaskell repeatedly. It's a simple job.

   1  runhaskell Setup.hs configure
   2  runhaskell Setup.hs build
   3  runhaskell Setup.hs install

If you are a Rubyist, you probably find the similarity between the command above and the usage of setup.rb. Do you know which is the chicken or the egg? :-)

About 30 minutes went by...

Finally, I got the cabal command.

See Also

• http://www.kotha.net/ghcguide_ja/latest/packages.htm