Resolving dependencies...
cabal: Could not resolve dependencies:
trying: prolog-graph-0.1.0.2 (user goal)
trying: graphviz-2999.18.0.1 (dependency of prolog-graph-0.1.0.2)
trying: containers-0.5.6.2/installed-2de... (dependency of
graphviz-2999.18.0.1)
next goal: prolog (dependency of prolog-graph-0.1.0.2)
rejecting: prolog-0.2.0.1 (conflict: prolog-graph => prolog==0.1.*)
rejecting: prolog-0.1 (conflict: containers==0.5.6.2/installed-2de..., prolog
=> containers>=0.4 && <0.5)
Backjump limit reached (change with --max-backjumps).