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: BiobaseHTTPTools-1.0.0 (user goal) [__1] trying: base-4.12.0.0/installed-4.1... (dependency of BiobaseHTTPTools) [__2] trying: BiobaseHTTP-1.1.0 (dependency of BiobaseHTTPTools) [__3] trying: Taxonomy-1.0.3 (dependency of BiobaseHTTP) [__4] trying: graphviz-2999.20.0.2 (dependency of Taxonomy) [__5] next goal: fgl (dependency of Taxonomy) [__5] rejecting: fgl-5.7.0.1, fgl-5.7.0.0 (conflict: graphviz => fgl>=5.4 && <5.7) [__5] rejecting: fgl-5.6.0.0 (conflict: base==4.12.0.0/installed-4.1..., fgl => base<4.12) [__5] rejecting: fgl-5.5.3.1, fgl-5.5.3.0, fgl-5.5.2.3, fgl-5.5.2.2, fgl-5.5.2.1, fgl-5.5.2.0, fgl-5.5.1.0, fgl-5.5.0.1, fgl-5.5.0.0, fgl-5.4.2.4, fgl-5.4.2.3, fgl-5.4.2.2, fgl-5.4.2.0, fgl-5.4.1.1, fgl-5.3 (conflict: Taxonomy => fgl>=5.5.4.0) [__5] rejecting: fgl-5.5.4.0 (conflict: base==4.12.0.0/installed-4.1..., fgl => base<4.12) [__5] fail (backjumping, conflict set: Taxonomy, base, fgl, graphviz) After searching the rest of the dependency tree exhaustively, these were the goals I've had most trouble fulfilling: Taxonomy, fgl, graphviz, base, BiobaseHTTP, BiobaseHTTPTools