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: tokenizer-streaming-0.1.0.0 (user goal) [__1] next goal: tokenizer-monad (dependency of tokenizer-streaming) [__1] rejecting: tokenizer-monad-0.2.1.0, tokenizer-monad-0.2.0.0, tokenizer-monad-0.1.0.0 (conflict: tokenizer-streaming => tokenizer-monad^>=0.2.2.0) [__1] fail (backjumping, conflict set: tokenizer-monad, tokenizer-streaming) After searching the rest of the dependency tree exhaustively, these were the goals I've had most trouble fulfilling: tokenizer-streaming, tokenizer-monad