[xmonad] Cabal compiles twice?

[Michael F. Lamb]

Hello all,

Whenever I compile Xmonad using cabal, it seems to compile twice. I'm 
new to haskell so perhaps I just don't understand what I'm looking at:

> $ runhaskell Setup configure --prefix=$HOME/usr --user
> Configuring xmonad-0.6...
> $ runhaskell Setup build
> Preprocessing library xmonad-0.6...
> Preprocessing executables for xmonad-0.6...
> Building xmonad-0.6...
> [1 of 8] Compiling XMonad.StackSet  ( XMonad/StackSet.hs, dist/build/XMonad/StackSet.o )
> [2 of 8] Compiling XMonad.Core      ( XMonad/Core.hs, dist/build/XMonad/Core.o )
> [3 of 8] Compiling XMonad.Layout    ( XMonad/Layout.hs, dist/build/XMonad/Layout.o )
> [4 of 8] Compiling XMonad.Operations ( XMonad/Operations.hs, dist/build/XMonad/Operations.o )
> [5 of 8] Compiling XMonad.ManageHook ( XMonad/ManageHook.hs, dist/build/XMonad/ManageHook.o )
> [6 of 8] Compiling XMonad.Config    ( XMonad/Config.hs, dist/build/XMonad/Config.o )
> [7 of 8] Compiling XMonad.Main      ( XMonad/Main.hs, dist/build/XMonad/Main.o )
> [8 of 8] Compiling XMonad           ( XMonad.hs, dist/build/XMonad.o )
> /usr/bin/ar: creating dist/build/libHSxmonad-0.6.a
> [ 1 of 10] Compiling Paths_xmonad     ( dist/build/autogen/Paths_xmonad.hs, dist/build/xmonad/xmonad-tmp/Paths_xmonad.o )
> [ 2 of 10] Compiling XMonad.StackSet  ( XMonad/StackSet.hs, dist/build/xmonad/xmonad-tmp/XMonad/StackSet.o )
> [ 3 of 10] Compiling XMonad.Core      ( XMonad/Core.hs, dist/build/xmonad/xmonad-tmp/XMonad/Core.o )
> [ 4 of 10] Compiling XMonad.Layout    ( XMonad/Layout.hs, dist/build/xmonad/xmonad-tmp/XMonad/Layout.o )
> [ 5 of 10] Compiling XMonad.Operations ( XMonad/Operations.hs, dist/build/xmonad/xmonad-tmp/XMonad/Operations.o )
> [ 6 of 10] Compiling XMonad.ManageHook ( XMonad/ManageHook.hs, dist/build/xmonad/xmonad-tmp/XMonad/ManageHook.o )
> [ 7 of 10] Compiling XMonad.Config    ( XMonad/Config.hs, dist/build/xmonad/xmonad-tmp/XMonad/Config.o )
> [ 8 of 10] Compiling XMonad.Main      ( XMonad/Main.hs, dist/build/xmonad/xmonad-tmp/XMonad/Main.o )
> [ 9 of 10] Compiling XMonad           ( XMonad.hs, dist/build/xmonad/xmonad-tmp/XMonad.o )
> [10 of 10] Compiling Main             ( ./Main.hs, dist/build/xmonad/xmonad-tmp/Main.o )
> Linking dist/build/xmonad/xmonad ...
> $

Shouldn't the /usr/bin/ar step use
   dist/build/XMonad/StackSet.o
rather than compile again to
   dist/build/xmonad/xmonad-tmp/XMonad/StackSet.o
?
Am I doing something wrong, or is this normal? If it is the norm, I'd
appreciate a link to where I can learn about why it's not doing what I'd
expect.

I'm hoping I might save my poor, slow laptop from a lot of hard thinking
every time I re-compile.

Thanks
-- 
Mike