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 (constraint from user target requires ==4.1.2) trying: pipes-4.1.2 trying: base-4.9.0.0/installed-4.9... (dependency of pipes-4.1.2) trying: mtl-2.2.1 (dependency of pipes-4.1.2) trying: transformers-compat-0.5.1.4 (dependency of mmorph-1.0.6) next goal: transformers (dependency of pipes-4.1.2) rejecting: transformers-0.5.2.0/installed-0.5..., transformers-0.5.2.0, transformers-0.5.1.0, transformers-0.5.0.1, transformers-0.5.0.0 (conflict: pipes => transformers>=0.2.0.0 && <0.5) rejecting: transformers-0.4.3.0, transformers-0.4.2.0 (conflict: base==4.9.0.0/installed-4.9..., transformers => base>=2 && <4.9) rejecting: transformers-0.4.1.0 (conflict: base==4.9.0.0/installed-4.9..., transformers => base>=2 && <4.8 || >=1.0 && <2) rejecting: transformers-0.3.0.0, transformers-0.2.2.1, transformers-0.2.1.0, transformers-0.2.0.0 (conflict: mtl => transformers>=0.4 && <0.6) rejecting: transformers-0.1.4.0, transformers-0.1.3.0, transformers-0.1.1.0, transformers-0.1.0.1, transformers-0.0.1.0, transformers-0.0.0.0, transformers-0.5.0.2 (conflict: pipes => transformers>=0.2.0.0 && <0.5) rejecting: transformers-0.4.0.0 (conflict: transformers-compat => transformers>=0.3 && <0.4 || >=0.2 && <0.3 || >=0.4.1 && <0.6) rejecting: transformers-0.2.2.0 (conflict: mtl => transformers>=0.4 && <0.6) rejecting: transformers-0.1.0.0 (conflict: pipes => transformers>=0.2.0.0 && <0.5) Dependency tree exhaustively searched.