[Hackage] #487: print less useless info during builds

[Hackage]

#487: print less useless info during builds
------------------------------+---------------------------------------------
  Reporter:  duncan           |        Owner:         
      Type:  enhancement      |       Status:  new    
  Priority:  normal           |    Milestone:         
 Component:  Cabal library    |      Version:  1.6.0.1
  Severity:  minor            |     Keywords:         
Difficulty:  easy (<4 hours)  |   Ghcversion:         
  Platform:                   |  
------------------------------+---------------------------------------------
 Here's an example from a blog post:

 {{{
 $ cabal update
 $ cabal install gofer-prelude
 Resolving dependencies...
 Downloading gofer-prelude-2.30...
 Configuring gofer-prelude-2.30...
 Preprocessing library gofer-prelude-2.30...
 Building gofer-prelude-2.30...
 [1 of 1] Compiling Prelude.Gofer    ( Prelude/Gofer.hs,
 dist/build/Prelude/Gofer.o )
 /usr/bin/ar: creating dist/build/libHSgofer-prelude-2.30.a
 Installing library in /home/dons/.cabal/lib/gofer-prelude-2.30/ghc-6.10.1
 Registering gofer-prelude-2.30...
 Reading package info from "dist/installed-pkg-config" ... done.
 Writing new package config file... done.
 }}}

 Which bits are useful and useless? I mean at the standard verbosity level.

 I bet this is useless:
 {{{
 Preprocessing library gofer-prelude-2.30...
 }}}
 Does it actually do any pre-processing? See also #475.

 Useless:
 {{{
 /usr/bin/ar: creating dist/build/libHSgofer-prelude-2.30.a
 }}}
 This is produced by the `ar` program. We can however pass it a flag to
 tell it to be quiet.

 Not especially useful:
 {{{
 Installing library in /home/dons/.cabal/lib/gofer-prelude-2.30/ghc-6.10.1
 }}}
 This message is generated by Cabal. At the default verbosity level we
 probably only need something like "Installing gofer-prelude-2.30..."

 Useless:
 {{{
 Reading package info from "dist/installed-pkg-config" ... done.
 Writing new package config file... done.
 }}}
 This message is generated by ghc-pkg. We should patch ghc-pkg to not be so
 verbose by default. That message is only needed at a higher verbosity
 level.

 So if we get all these things fixed it'd look like:
 {{{
 $ cabal update
 Downloading package list from hackage.haskell.org
 $ cabal install gofer-prelude
 Resolving dependencies...
 Downloading gofer-prelude-2.30...
 Configuring gofer-prelude-2.30...
 Building gofer-prelude-2.30...
 [1 of 1] Compiling Prelude.Gofer    ( Prelude/Gofer.hs,
 dist/build/Prelude/Gofer.o )
 Installing gofer-prelude-2.30...
 Registering gofer-prelude-2.30...
 }}}

 This is assuming the package in question doesn't actually need any pre-
 processing. Even the pre-processing message could be elided if we don't
 think it'll take that long.

 I wonder if we can get ghc to not tell us the source and object file
 locations. While it is sometimes useful while hacking, for batch builds we
 do not need it.

-- 
Ticket URL: <http://hackage.haskell.org/trac/hackage/ticket/487>
Hackage <http://haskell.org/cabal/>
Hackage: Cabal and related projects