Resolving dependencies...
cabal: Could not resolve dependencies:
next goal: xmonad (user goal)
rejecting: xmonad-0.12, xmonad-0.11.1, xmonad-0.11, xmonad-0.10, xmonad-0.9.2,
xmonad-0.9.1, xmonad-0.9, xmonad-0.8.1, xmonad-0.8, xmonad-0.7, xmonad-0.6,
xmonad-0.5, xmonad-0.4.1 (constraint from user target requires ==0.4)
trying: xmonad-0.4
next goal: base (dependency of xmonad-0.4)
rejecting: base-4.9.0.0/installed-4.9... (conflict: xmonad => base>=2.0 && <3)
rejecting: base-4.9.0.0, base-4.8.2.0, base-4.8.1.0, base-4.8.0.0,
base-4.7.0.2, base-4.7.0.1, base-4.7.0.0, base-4.6.0.1, base-4.6.0.0,
base-4.5.1.0, base-4.5.0.0, base-4.4.1.0, base-4.4.0.0, base-4.3.1.0,
base-4.3.0.0, base-4.2.0.2, base-4.2.0.1, base-4.2.0.0, base-4.1.0.0,
base-4.0.0.0, base-3.0.3.2, base-3.0.3.1 (constraint from non-upgradeable
package requires installed instance)
Dependency tree exhaustively searched.