[xmonad] Trouble configuring xmonad on gentoo

[Nathan Huesken]

Hello together,

I am new to xmonad. I installed it on my gentoo system using the haskell
overlay and "emerge xmonad".

No I want to change the configuration:
I tried uncommenting the following lines in
/etc/portage/savedconfig/x11-wm/xmonad-0.4.1:

(Line 69)
import qualified XMonadContrib.HintedTile
(Line 248)
, XMonadContrib.HintedTile.tall nmaster delta ratio

and did emerge -av xmonad:
Calculating dependencies... done!
[ebuild   R   ] x11-wm/xmonad-0.4.1  USE="extensions savedconfig" 0 kB
(...)
Building xmonad-0.4.1...
[1 of 7] Compiling StackSet         ( StackSet.hs,
dist/build/xmonad/xmonad-tmp/StackSet.o )
[2 of 7] Compiling XMonad           ( XMonad.hs,
dist/build/xmonad/xmonad-tmp/XMonad.o )
[3 of 7] Compiling Config[boot]     ( Config.hs-boot, nothing )
[4 of 7] Compiling Operations       ( Operations.hs,
dist/build/xmonad/xmonad-tmp/Operations.o )
[5 of 7] Compiling XMonadContrib.HintedTile (
XMonadContrib/HintedTile.hs,
dist/build/xmonad/xmonad-tmp/XMonadContrib/HintedTile.o )

XMonadContrib/HintedTile.hs:55:13: Not in scope: `modifyLayout'

What am I doing wrong?
Thanks!
nathan