Resolving dependencies...
cabal: Could not resolve dependencies:
next goal: graph-rewriting-ski (user goal)
rejecting: graph-rewriting-ski-0.6.5, graph-rewriting-ski-0.6.4,
graph-rewriting-ski-0.6.3, graph-rewriting-ski-0.6.2,
graph-rewriting-ski-0.6.1, graph-rewriting-ski-0.5.7,
graph-rewriting-ski-0.5.6, graph-rewriting-ski-0.5.4,
graph-rewriting-ski-0.5.2, graph-rewriting-ski-0.5.1, graph-rewriting-ski-0.5,
graph-rewriting-ski-0.4.7, graph-rewriting-ski-0.4.5,
graph-rewriting-ski-0.4.4 (constraint from user target requires ==0.4.3)
trying: graph-rewriting-ski-0.4.3
next goal: base (dependency of graph-rewriting-ski-0.4.3)
rejecting: base-4.9.0.0/installed-4.9... (conflict: graph-rewriting-ski =>
base>=4 && <4.3)
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.