Make it easy to find documentation for GHC and installed packages

[simonpj]

ghc-pkg builds a package database that helps GHC find all installed packages. But it'd be a great improment if the same step also helped the user find the Haddock documentation for all installed packages.

Corresponding to GHC's package database would be an HTML page that is a single point of entry for the user to find documentation about installed packages. Preferably together with a consolidated index. (And maybe ghc --help should give the local URL of this documentation root.)

[claus]

there are also other tools who'd like easy access to that information, on behalf of the user;-) for instance, one of my haskell mode plugins for vim uses haddock's index to figure out which haskell identifiers have documentation, and where to find it:

 haskell_doc.vim

one would like at least a central html table of contents plus a central index for the user, plus a more accessible format of the index for ide-like tools. currently, the toc and index contain all packages built together with ghc, but the information in the index isn't easily accessible for tools. preferably, added packages should integrate their toc and index with the central ones (or include the central ones into their own central toc and index, if they are a user-build).

also, i have found that ghc-pkg reports where the docs *might* be, even if they aren't installed! perhaps there should be a separate documentation package associated with each binary package?

this is also related to #1226 (finding ghc user_guide installed location).

[igloo]

We should also try to integrate this with the system-specific central documentation system, when such a thing exists.

[alpmestan]

This is partly handled by cabal (when the appropriate option is enabled, either in the config file or using command line arguments). For instance, my ~/.cabal/share/doc/index.html file does the job, for the user at least, even if it's modules-centered, not package-centered.

Are you people still interested in what Simon suggested ? Would that mean moving some stuffs from cabal to GHC, and extending them for what Claus described ?

[simonmar]

It's basically hooking up our documentation to whatever the system's convention for documentation is. e.g. on Windows we already have a start menu entry for GHC's documentation, but we should also have one for Cabal-generated documentation. On Linux I'm not sure - GHC's documentation often comes in a separate package and just gets dumped somewhere like /usr/share/doc/ghc, there doesn't seem to be a central place to get at application documentation, at least on Ubuntu.

[igloo]

For Debian, and presumably ubuntu, there's the doc-base package. But GHC shouldn't worry about that: the packagers will.

[morabbin]

Bump. I agree with Ian re packages doco, but where are we with GHC docs?