Warning: The install command is a part of the legacy v1 style of cabal usage. Please switch to using either the new project style and the new-install command or the legacy v1-install alias as new-style projects will become the default in the next version of cabal-install. Please file a bug if you cannot replicate a working v1- use case with the new-style commands. For more information, see: https://wiki.haskell.org/Cabal/NewBuild Resolving dependencies... cabal: Could not resolve dependencies: [__0] trying: classify-frog-0.2.4.3 (user goal) [__1] trying: transformers-0.5.5.0/installed-0.5... (dependency of classify-frog) [__2] next goal: soxlib (dependency of classify-frog) [__2] rejecting: soxlib-0.0.3.1, soxlib-0.0.3 (conflict: pkg-config package sox>=14.3 && <14.5, not found in the pkg-config database) [__2] rejecting: soxlib-0.0.2.1, soxlib-0.0.2, soxlib-0.0.1.2, soxlib-0.0.1.1 (conflict: transformers==0.5.5.0/installed-0.5..., soxlib => transformers>=0.2 && <0.5) [__2] rejecting: soxlib-0.0.1, soxlib-0.0 (conflict: transformers==0.5.5.0/installed-0.5..., soxlib => transformers>=0.2 && <0.4) [__2] fail (backjumping, conflict set: classify-frog, soxlib, transformers) After searching the rest of the dependency tree exhaustively, these were the goals I've had most trouble fulfilling: soxlib, transformers, base, classify-frog