Resolving dependencies...
Error: cabal: Could not resolve dependencies:
[__0] next goal: webp (user goal)
[__0] rejecting: webp-0.1.1.0 (conflict: pkg-config package libwebp>=0.6.1,
not found in the pkg-config database)
[__0] rejecting: webp-0.1.0.3, webp-0.1.0.2, webp-0.1.0.1, webp-0.1.0.0
(constraint from user target requires ==0.1.1.0)
[__0] fail (backjumping, conflict set: webp)
After searching the rest of the dependency tree exhaustively, these were the
goals I've had most trouble fulfilling: webp