Resolving dependencies... cabal: Could not resolve dependencies: next goal: Frank (user goal) rejecting: Frank-0.3, Frank-0.2 (constraint from user target requires ==0.1) trying: Frank-0.1 trying: base-4.9.0.0/installed-4.9... (dependency of Frank-0.1) next goal: she (dependency of Frank-0.1) rejecting: she-0.6, she-0.5, she-0.4 (conflict: base==4.9.0.0/installed-4.9..., she => base>=3 && <4.6) trying: she-0.3 next goal: mtl (dependency of Frank-0.1) rejecting: mtl-2.2.1, mtl-2.2.0.1, mtl-2.2, mtl-2.1.3.1, mtl-2.1.2, mtl-2.1.1, mtl-2.1, mtl-2.0.1.1, mtl-2.0.1.0, mtl-2.0.0.0, mtl-1.1.1.1, mtl-1.1.1.0, mtl-1.1.0.2, mtl-1.1.0.1, mtl-1.1.0.0 (conflict: she => mtl<1.1) rejecting: mtl-1.0 (conflict: base==4.9.0.0/installed-4.9..., mtl => base<4.3) Dependency tree exhaustively searched.