cabal exec -- ghc-mod browse Data.Map
>>> /differenceWithKey/
>>>= 0

cabal exec -- ghc-mod browse -d Data.Either
>>> /^either :: \(a -> c\) -> \(b -> c\) -> Either a b -> c$/
>>>= 0

cabal exec -- ghc-mod browse -d Data.Either
>>> /^Left :: a -> Either a b$/
>>>= 0