cabal: cannot configure checkers-0.2.7. It requires base <4.3
For the dependency on base <4.3 there are these packages: base-3.0.3.1,
base-3.0.3.2, base-4.0.0.0, base-4.1.0.0, base-4.2.0.0, base-4.2.0.1 and
base-4.2.0.2. However none of them are available.
base-3.0.3.1 was excluded because base-4.3.0.0 was selected instead
base-3.0.3.1 was excluded because of the top level dependency base -any
base-3.0.3.2 was excluded because base-4.3.0.0 was selected instead
base-3.0.3.2 was excluded because of the top level dependency base -any
base-4.0.0.0 was excluded because base-4.3.0.0 was selected instead
base-4.0.0.0 was excluded because of the top level dependency base -any
base-4.1.0.0 was excluded because base-4.3.0.0 was selected instead
base-4.1.0.0 was excluded because of the top level dependency base -any
base-4.2.0.0 was excluded because base-4.3.0.0 was selected instead
base-4.2.0.0 was excluded because of the top level dependency base -any
base-4.2.0.1 was excluded because base-4.3.0.0 was selected instead
base-4.2.0.1 was excluded because of the top level dependency base -any
base-4.2.0.2 was excluded because base-4.3.0.0 was selected instead
base-4.2.0.2 was excluded because of the top level dependency base -any