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: symbiote-0.0.2 (user goal) [__1] next goal: zeromq4-haskell (dependency of symbiote) [__1] rejecting: zeromq4-haskell-0.8.0, zeromq4-haskell-0.7.0, zeromq4-haskell-0.6.7, zeromq4-haskell-0.6.6, zeromq4-haskell-0.6.5, zeromq4-haskell-0.6.4, zeromq4-haskell-0.6.3, zeromq4-haskell-0.6.2, zeromq4-haskell-0.6.1, zeromq4-haskell-0.6, zeromq4-haskell-0.5.1, zeromq4-haskell-0.5, zeromq4-haskell-0.4.1, zeromq4-haskell-0.4, zeromq4-haskell-0.3.2, zeromq4-haskell-0.3.1, zeromq4-haskell-0.3 (conflict: pkg-config package libzmq>=4.0 && <5.0, not found in the pkg-config database) [__1] trying: zeromq4-haskell-0.2 [__2] trying: transformers-0.5.5.0/installed-0.5... (dependency of zeromq4-haskell) [__3] next goal: MonadCatchIO-transformers (dependency of zeromq4-haskell) [__3] rejecting: MonadCatchIO-transformers-0.3.1.3 (conflict: transformers => base==4.12.0.0/installed-4.1..., MonadCatchIO-transformers => base<4.9) [__3] rejecting: MonadCatchIO-transformers-0.3.1.2, MonadCatchIO-transformers-0.3.1.1, MonadCatchIO-transformers-0.3.1.0 (conflict: transformers => base==4.12.0.0/installed-4.1..., MonadCatchIO-transformers => base<4.8) [__3] rejecting: MonadCatchIO-transformers-0.3.0.0, MonadCatchIO-transformers-0.2.2.3, MonadCatchIO-transformers-0.2.2.2, MonadCatchIO-transformers-0.2.2.1, MonadCatchIO-transformers-0.2.2.0, MonadCatchIO-transformers-0.2.1.0, MonadCatchIO-transformers-0.2.0.0 (conflict: transformers => base==4.12.0.0/installed-4.1..., MonadCatchIO-transformers => base<4.7) [__3] rejecting: MonadCatchIO-transformers-0.1.0.1 (conflict: transformers==0.5.5.0/installed-0.5..., MonadCatchIO-transformers => transformers==0.1.*) [__3] rejecting: MonadCatchIO-transformers-0.1.0.0, MonadCatchIO-transformers-0.0.2.0, MonadCatchIO-transformers-0.0.1.0 (conflict: transformers==0.5.5.0/installed-0.5..., MonadCatchIO-transformers => transformers<0.2) [__3] fail (backjumping, conflict set: MonadCatchIO-transformers, transformers, zeromq4-haskell) After searching the rest of the dependency tree exhaustively, these were the goals I've had most trouble fulfilling: MonadCatchIO-transformers, base, transformers, zeromq4-haskell, symbiote