Resolving dependencies...
Starting     hex-0.2.0
Building     hex-0.2.0
Failed to install hex-0.2.0
Build log ( /home/builder/.cabal/logs/ghc-8.6.3/hex-0.2.0-IvFtD6BWszz4w9QygNnyFQ.log ):
cabal: Entering directory '/tmp/cabal-tmp-13934/hex-0.2.0'
Configuring hex-0.2.0...
Preprocessing library for hex-0.2.0..
Building library for hex-0.2.0..
[1 of 1] Compiling Data.Hex         ( Data/Hex.hs, dist/build/Data/Hex.o )

Data/Hex.hs:28:15: error:
    Not in scope: type constructor or class ‘MonadFail’
   |
28 |     unhexM :: MonadFail m => t -> m t
   |               ^^^^^^^^^
cabal: Leaving directory '/tmp/cabal-tmp-13934/hex-0.2.0'
cabal: Error: some packages failed to install:
hex-0.2.0-IvFtD6BWszz4w9QygNnyFQ failed during the building phase. The
exception was:
ExitFailure 1