Resolving dependencies...
cabal: Could not resolve dependencies:
next goal: happstack-heist (user goal)
rejecting: happstack-heist-7.2.4, 7.2.3, 7.2.2, 7.2.1, 7.2.0, 7.1.2, 7.1.1,
7.1.0, 7.0.2, 7.0.1, 7.0.0 (global constraint requires ==6.0.7)
trying: happstack-heist-6.0.7
trying: mtl-2.2.1 (dependency of happstack-heist-6.0.7)
next goal: heist (dependency of happstack-heist-6.0.7)
rejecting: heist-0.14.1, 0.14.0.1, 0.14.0, 0.13.1.2, 0.13.1.1, 0.13.1,
0.13.0.6, 0.13.0.5, 0.13.0.4, 0.13.0.3, 0.13.0.2, 0.13.0.1, 0.13.0, 0.12.0,
0.11.1, 0.11.0.1, 0.11.0, 0.10.2.1, 0.10.2, 0.10.1, 0.10.0, 0.8.2, 0.8.1.1,
0.8.1, 0.8.0 (conflict: happstack-heist => heist>=0.5 && <0.8)
rejecting: heist-0.7.0.1, 0.7.0, 0.6.1, 0.6.0.1, 0.6.0, 0.5.3, 0.5.2.1, 0.5.2,
0.5.1.1, 0.5.1.0, 0.5.0.1, 0.5.0.0 (conflict: mtl==2.2.1, heist => mtl>=2.0 &&
<2.1)
rejecting: heist-0.4.0.1, 0.4.0.0, 0.3.0.0, 0.2.4, 0.2.3, 0.2.2, 0.2.1, 0.2.0,
0.1.2, 0.1.1 (conflict: happstack-heist => heist>=0.5 && <0.8)
Dependency tree exhaustively searched.