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: pandoc-citeproc-0.16.3.1 (user goal)
[__1] trying: pandoc-2.7.3 (dependency of pandoc-citeproc)
[__2] next goal: haddock-library (dependency of pandoc)
[__2] rejecting: haddock-library-1.8.0 (conflict: pandoc =>
haddock-library>=1.7 && <1.8)
[__2] trying: haddock-library-1.7.0
[__3] trying: base-4.12.0.0/installed-4.1... (dependency of pandoc-citeproc)
[__4] next goal: HsYAML (dependency of pandoc-citeproc)
[__4] rejecting: HsYAML-0.2.1.0, HsYAML-0.2.0.0 (conflict: pandoc =>
HsYAML>=0.1.1.1 && <0.2)
[__4] rejecting: HsYAML-0.1.2.0, HsYAML-0.1.1.3, HsYAML-0.1.1.2,
HsYAML-0.1.1.1, HsYAML-0.1.1.0, HsYAML-0.1.0.0 (conflict: pandoc-citeproc =>
HsYAML>=0.2 && <0.3)
[__4] fail (backjumping, conflict set: HsYAML, pandoc, pandoc-citeproc)
After searching the rest of the dependency tree exhaustively, these were the
goals I've had most trouble fulfilling: pandoc, pandoc-citeproc, HsYAML,
haddock-library, base