Resolving dependencies...
cabal: Could not resolve dependencies:
next goal: pipes (user goal)
rejecting: pipes-4.2.0, pipes-4.1.9, pipes-4.1.8, pipes-4.1.7, pipes-4.1.6,
pipes-4.1.5, pipes-4.1.4, pipes-4.1.3, pipes-4.1.2, pipes-4.1.1, pipes-4.1.0
(constraint from user target requires ==4.0.2)
trying: pipes-4.0.2
trying: base-4.9.0.0/installed-4.9... (dependency of pipes-4.0.2)
next goal: void (dependency of pipes-4.0.2)
rejecting: void-0.7.1, void-0.7 (conflict: pipes => void<0.7)
rejecting: void-0.6.1, void-0.6, void-0.5.12, void-0.5.11, void-0.5.10,
void-0.5.8, void-0.5.7, void-0.5.6, void-0.5.5.1, void-0.5.5, void-0.5.4.3,
void-0.5.4.2, void-0.5.4.1, void-0.5.4, void-0.5.3, void-0.5.2, void-0.5.1,
void-0.5.0, void-0.4, void-0.3, void-0.2, void-0.1 (conflict:
base==4.9.0.0/installed-4.9..., void => base>=3 && <4.8)
Dependency tree exhaustively searched.