gistfile1.hs

hFetchLines :: Handle -> [Int] -> IO [String]
hFetchLines h nums = do; end <- hIsEOF h; hFetchLines' nums end 1 []
  where
    hFetchLines' [] _ _ acc = return acc
    hFetchLines' _ False _ acc = return acc
    hFetchLines' nums _ row acc = do
                 line <- hGetLine h
                 end <- hIsEOF h
                 if (head nums) == row
                   then hFetchLines' (tail nums) end (row+1) (line:acc)
                   else hFetchLines' nums end (row+1) acc