Haskell offline documentation?

Question

What are the possibilities, if any, for getting offline docs for Haskell core libraries (and maybe more)?

Sometimes I take my laptop to the coffee-shop where there is no

Answer 1

Hoogle is available offline, installable from Cabal: http://hackage.haskell.org/package/hoogle

Usage instructions are at http://www.haskell.org/haskellwiki/Hoogle#Command_Line_Search_Flags.

Usage:

$ hoogle --help
Hoogle v4.2.8, (C) Neil Mitchell 2004-2011
http://haskell.org/hoogle

hoogle [COMMAND] ... [OPTIONS]

Commands:
  [search]  Perform a search
  data      Generate Hoogle databases
  server    Start a Hoogle server
  combine   Combine multiple databases into one
  convert   Convert an input file to a database
  test      Run tests
  dump      Dump sections of a database to stdout
  rank      Generate ranking information
  log       Analyse log files

Common flags:
  -? --help     Display help message
  -V --version  Print version information
  -v --verbose  Loud verbosity
  -q --quiet    Quiet verbosity

Create a default database with hoogle data (more info at http://neilmitchell.blogspot.com/2008/08/hoogle-database-generation.html).

EDIT: A session of usage after installing Hoogle locally:

$ hoogle
No query entered
Try --help for command line options
$ hoogle data
(downloads databases...takes a few minutes)

I ran into an error here...apparently it is related to the version of Cabal, so I updated that (http://hackage.haskell.org/trac/hackage/ticket/811). That didn't help, so I ran hoogle data all, which I canceled since it was taking so long (it seems to go through every package on Hackage). It still wouldn't allow a query like hoogle map but did allow hoogle map +base (i.e. restrict the search to the base package) Hopefully it works for you!

EDIT2: This seems to fix the problem (for me):

$cd .cabal/share/hoogle-4.2.8/databases
$hoogle combine base.hoo
$hoogle foldl\'
Data.List foldl' :: (a -> b -> a) -> a -> [b] -> a
Data.Foldable foldl' :: Foldable t => (a -> b -> a) -> a -> t b -> a