Resolving dependencies... Error: cabal: Could not resolve dependencies: [__0] trying: tinytools-vty-0.1.0.7 (user goal) [__1] trying: tinytools-0.1.0.7 (dependency of tinytools-vty) [__2] trying: template-haskell-2.18.0.0/installed-2.18.0.0 (dependency of tinytools-vty) [__3] next goal: pretty (dependency of template-haskell) [__3] rejecting: pretty-1.1.3.6/installed-1.1.3.6 (conflict: tinytools => deepseq>=1.4.8 && <1.5, pretty => deepseq==1.4.6.1/installed-1.4.6.1) [__3] rejecting: pretty-1.1.3.6, pretty-1.1.3.5, pretty-1.1.3.4, pretty-1.1.3.3, pretty-1.1.3.2, pretty-1.1.3.1, pretty-1.1.2.1, pretty-1.1.2.0, pretty-1.1.1.3, pretty-1.1.1.2, pretty-1.1.1.1, pretty-1.1.1.0, pretty-1.1.0.0, pretty-1.0.1.2, pretty-1.0.1.1, pretty-1.0.1.0, pretty-1.0.0.0 (conflict: template-haskell => pretty==1.1.3.6/installed-1.1.3.6) [__3] fail (backjumping, conflict set: pretty, template-haskell, tinytools) After searching the rest of the dependency tree exhaustively, these were the goals I've had most trouble fulfilling: template-haskell, pretty, tinytools-vty, tinytools Try running with --minimize-conflict-set to improve the error message.