実行するcabal install hoogle
と、次のようになります。
setup: The program happy version >=1.17 is required but it could not be found
cabal: Error: some packages failed to install
haskell-src-exts-1.13.3 failed during the configure step the exeption is ExitFailure 1
$ghc -V
The Glorious Glasgow Haskell Compilation System, version 7.4.1
そのような問題を解決する方法は?