Resolving dependencies... cabal: Could not resolve dependencies: [__0] trying: sound-collage-0.2.1 (user goal) [__1] trying: transformers-0.5.6.2/installed-0.5.6.2 (dependency of sound-collage) [__2] next goal: soxlib (dependency of sound-collage) [__2] rejecting: soxlib-0.0.3.1, soxlib-0.0.3 (conflict: pkg-config package sox(==14.3 || >14.3) && <14.5, not found in the pkg-config database) [__2] rejecting: soxlib-0.0.2.1 (conflict: transformers==0.5.6.2/installed-0.5.6.2, soxlib => transformers>=0.2 && <0.5) [__2] skipping: soxlib-0.0.2, soxlib-0.0.1.2, soxlib-0.0.1.1, soxlib-0.0.1, soxlib-0.0 (has the same characteristics that caused the previous version to fail: excludes 'transformers' version 0.5.6.2) [__2] fail (backjumping, conflict set: sound-collage, soxlib, transformers) After searching the rest of the dependency tree exhaustively, these were the goals I've had most trouble fulfilling: transformers, soxlib, base, sound-collage Try running with --minimize-conflict-set to improve the error message.