Resolving dependencies... cabal: Could not resolve dependencies: [__0] trying: Allure-0.10.2.0 (user goal) [__1] trying: LambdaHack-0.10.2.0 (dependency of Allure) [__2] trying: LambdaHack:-jsaddle [__3] trying: LambdaHack:-vty [__4] trying: LambdaHack:-curses [__5] trying: LambdaHack:-gtk [__6] next goal: sdl2-ttf (dependency of LambdaHack -curses -gtk -jsaddle -vty) [__6] rejecting: sdl2-ttf-2.1.2, sdl2-ttf-2.1.1, sdl2-ttf-2.1.0 (conflict: pkg-config package SDL2_ttf==2.0.12 || >2.0.12, not found in the pkg-config database) [__6] rejecting: sdl2-ttf-2.0.2, sdl2-ttf-2.0.1, sdl2-ttf-2.0.0 (conflict: pkg-config package SDL2_ttf==2.0.0 || >2.0.0, not found in the pkg-config database) [__6] rejecting: sdl2-ttf-1.0.0, sdl2-ttf-0.2.2, sdl2-ttf-0.2.1, sdl2-ttf-0.2.0 (conflict: LambdaHack -curses -gtk -jsaddle -vty => sdl2-ttf>=2) [__6] fail (backjumping, conflict set: LambdaHack, sdl2-ttf, LambdaHack:curses, LambdaHack:gtk, LambdaHack:jsaddle, LambdaHack:vty) After searching the rest of the dependency tree exhaustively, these were the goals I've had most trouble fulfilling: Allure, LambdaHack, sdl2-ttf, LambdaHack:curses, LambdaHack:gtk, LambdaHack:jsaddle, LambdaHack:vty Try running with --minimize-conflict-set to improve the error message.