Resolving dependencies...
cabal: Could not resolve dependencies:
trying: gruff-examples-0.3.1 (user goal)
trying: base-4.8.1.0/installed-4f7... (dependency of gruff-examples-0.3.1)
trying: gruff-0.3.4 (dependency of gruff-examples-0.3.1)
next goal: OpenGL (dependency of gruff-0.3.4)
rejecting: OpenGL-2.13.0.0, 2.12.0.1, 2.12.0.0, 2.11.1.0, 2.11.0.0, 2.10.0.2,
2.10.0.1, 2.10.0.0 (conflict: gruff => OpenGL>=2.9 && <2.10)
rejecting: OpenGL-2.9.2.0, 2.9.1.0, 2.9.0.0 (conflict:
base==4.8.1.0/installed-4f7..., OpenGL => base>=3 && <4.8)
rejecting: OpenGL-2.8.0.0, 2.6.0.1, 2.6.0.0, 2.5.0.0, 2.4.0.2, 2.4.0.1,
2.4.0.0, 2.3.0.0, 2.2.3.1, 2.2.3.0, 2.2.2.0, 2.2.1.1, 2.1 (conflict: gruff =>
OpenGL>=2.9 && <2.10)
Backjump limit reached (change with --max-backjumps).