Resolving dependencies...
cabal: Could not resolve dependencies:
[__0] trying: ghc-api-compat-9.0.1 (user goal)
[__1] next goal: ghc (dependency of ghc-api-compat)
[__1] rejecting: ghc-8.10.2/installed-8.10.2 (conflict: ghc-api-compat =>
ghc==9.0.*)
[__1] skipping: ghc-8.10.2, ghc-8.10.1, ghc-8.8.3, ghc-8.8.1, ghc-8.6.5,
ghc-8.6.4, ghc-8.6.1, ghc-8.4.4, ghc-8.4.3, ghc-8.4.1, ghc-8.2.2, ghc-8.2.1
(has the same characteristics that caused the previous version to fail:
excluded by constraint '==9.0.*' from 'ghc-api-compat')
[__1] fail (backjumping, conflict set: ghc, ghc-api-compat)
After searching the rest of the dependency tree exhaustively, these were the
goals I've had most trouble fulfilling: ghc-api-compat, ghc