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] next goal: gtk (user goal) [__0] rejecting: gtk-0.15.4 (conflict: pkg-config package gtk+-2.0-any, not found in the pkg-config database) [__0] rejecting: gtk-0.15.3, gtk-0.15.2, gtk-0.15.1, gtk-0.15.0, gtk-0.14.7, gtk-0.14.6, gtk-0.14.5, gtk-0.14.4, gtk-0.14.3, gtk-0.14.2, gtk-0.13.9, gtk-0.13.8.1, gtk-0.13.8, gtk-0.13.7, gtk-0.13.6, gtk-0.13.4, gtk-0.13.3, gtk-0.13.2, gtk-0.13.1, gtk-0.13.0.3, gtk-0.13.0.2, gtk-0.13.0.1, gtk-0.13.0.0, gtk-0.12.5.7, gtk-0.12.5.6, gtk-0.12.5.5, gtk-0.12.5.4, gtk-0.12.5.3, gtk-0.12.5.2, gtk-0.12.5.1, gtk-0.12.5.0, gtk-0.12.4, gtk-0.12.3.1, gtk-0.12.3, gtk-0.12.2, gtk-0.12.1, gtk-0.12.0, gtk-0.11.2, gtk-0.11.1, gtk-0.11.0, gtk-0.14.10, gtk-0.14.9 (constraint from user target requires ==0.15.4) [__0] fail (backjumping, conflict set: gtk) After searching the rest of the dependency tree exhaustively, these were the goals I've had most trouble fulfilling: gtk