Lost in Technopolis

by John Wiegley

Running a fully local Hoogle

Posted by John Wiegley on September 5, 2012 with labels:

Today I finally succeeded at getting a fully local version of Hoogle running on my machine, with filesystem links for all packages that I have installed, and remote links for those I don’t. Since this was definitely a non-trivial exercise, I wanted to capture the knowledge here for anyone else trying to do the same.

First, let me mention that I’m using OS X 10.7.4, GHC 7.4.2 (64-bit), and Hoogle 4.2.13. I had to install Hoogle from source in order to apply the following patch:

--- a/src/CmdLine/All.hs
+++ b/src/CmdLine/All.hs
@@ -74,6 +74,7 @@ guessLocal = do
     lib <- getLibDir
     let xs = [takeDirectory (takeDirectory lib) </> "doc" {- Windows, installed with Cabal -}  ] ++
              [takeDirectory (takeDirectory ghc) </> "doc/html/libraries" | Just ghc <- [ghc] {- Windows, installed by GHC -} ] ++
+             [takeDirectory (takeDirectory ghc) </> "share/doc/ghc/html/libraries" | Just ghc <- [ghc] {- Mac OS X, installed by GHC -} ] ++
              [home </> ".cabal/share/doc" {- Linux -} ]
     filterM doesDirectoryExist xs

This allows Hoogle’s data command find my GHC library documentation in $GHCROOT/share/doc/ghc/html/libraries. Otherwise, none of the standard libraries show up as local links in the search results. Then I built and installed Hoogle:

cabal configure
cabal install

The next step was to enable Haddock Documentation for all packages I locally install with cabal. This required editing ~/.cabal/config and making sure the following line was present:

documentation: True

While you’re at, go ahead and enable library profiling too, so you have profiling libs available the next time you want to hunt down a space leak:

library-profiling: True

Unfortunately these two are not the default, so if you’re adding them now you’ll have to rebuild every package in your local repository:

cabal install world --reinstall --force-reinstalls

This could take awhile – and may not complete successfully. I had more luck at wiping my old state and starting over:

cp ~/.cabal/config ~/.cabal/world /tmp
rm ~/.cabal ~/.ghc
cd 
sh bootstrap.sh
cp /tmp/config /tmp/world ~/.cabal
cabal update
cabal install world

I also edited bootstrap.sh to make sure that the libraries installed by this process also haddocumentation and profiling libs available. Make sure you add the following line to the top of bootstrap.sh:

EXTRA_CONFIGURE_OPTS=--enable-library-profiling

And these lines right after the Setup build invocation:

./Setup haddock ${VERBOSE} \
  || die "Haddocking the ${PKG} package failed"

Even after all this you may need to intervene manually, if some of your packages require special options to build. For example, I always need -f have-quartz-gtk to build gtk, but it seems Cabal doesn’t remember this in my world file, and so gtk breaks every time anything tries to rebuild it.

Back to Hoogle. By now you should have two things: a hoogle binary, and a fset of local documentation in ~/.cabal/share/doc. Make sure that you do, before going any further. Then, download and generate all the necessary Hoogle data, with local annotations where possible:

hoogle data -l -r all

If you only want a subset of hoogle, drop the all keyword. This process takes a long time, so head out and get some coffee! Once this is finished – and after any time you run this command to reflect newly install new packages – ensure that your default.hoo database is also up-to-date. Here’s how I did that:

cd ~/.cabal/share/hoogle-4.2.13/databases
mv default.hoo default.hoo-prev
hoogle combine *.hoo

On my system this merged 3377 database, took an exceedingly long time, and used almost 7 gigabytes of RAM. It is a much longer process than the data command above. But once it’s done you can now run:

sudo hoogle server --local

And voila! You should be able to query Hoogle and browse documentation fully offline, as long as you’ve installed the related packages. Even further, you can add this to your .ghci file:

:def h \x -> return $ ":!hoogle -c -n 10 \"" ++ x ++ "\""
:def doc \x -> return $ ":!hoogle --info \"" ++ x ++ "\""

And be able to type :h a -> a to query the top ten hits in Hoogle, fully syntax-highlighted (if your terminal supports it), and :doc head to read the documentation for the first match on head.


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