Resolving dependencies...
Downloading BNFC-2.4.2.0...
Configuring BNFC-2.4.2.0...
Building BNFC-2.4.2.0...
Preprocessing executable 'bnfc' for BNFC-2.4.2.0...

Main.hs:1:1:
    Ambiguous module name `Prelude':
      it was found in multiple packages: base haskell98-2.0.0.2
Failed to install BNFC-2.4.2.0
cabal: Error: some packages failed to install:
BNFC-2.4.2.0 failed during the building phase. The exception was:
ExitFailure 1