DouKaku?

import Data.List
import Data.Ord
import System.Process

data ClassInfo = CI { className :: String, numberOfMethods :: Int }

main = do { res <- readProcess "ghc" ["-e",":browse Prelude"] []
          ; let cis = classInfos [] $ lines res
          ; let n = length cis
          ; putStr $ unlines {- $ take 10 -}
          $ map showClassInfo $ sortBy (flip (comparing numberOfMethods)) cis
          ; putStr $ unlines ["...","number of classes : "++show n]
          }

showClassInfo :: ClassInfo -> String
showClassInfo (CI name n) = name ++ " (" ++ show n ++ ")"

classInfos :: [ClassInfo] -> [String] -> [ClassInfo]
classInfos a [] = a
classInfos a (l:ls)
 | head lw /= "class" = classInfos a ls
 | otherwise = classInfos (ci:a) ls''
   where 
     lw = words l
     ci = CI name (if null ls' then 1 else length ls')
     (ls',ls'') = break (not . ("  " `isPrefixOf`)) ls
     name = case break ("=>"==) lw of
       (_,[])  -> head $ tail lw
       (_,lw') -> head $ tail lw'