Haskell Snippet: read CSV file, marshall into type

This listing shows how to open a file, extract the contents, split by the delimiter (regex is a little off) and then mashall into a datatype.


data PageURLFieldInfo = PageURLFieldInfo {
      linkUrlField :: String, 
      aUrlField :: Integer, 
      blockquoteUrlField :: Integer,
      divUrlField :: Integer,
      h1UrlField :: Integer,
      imgUrlField :: Integer,
      pUrlField :: Integer,
      strongUrlField :: Integer,
      tableUrlField :: Integer
}
--
-- The info content file contains html document information.
-- It may not exist but should, also contains URL info.
readInfoContentFile :: String -> IO PageURLFieldInfo
readInfoContentFile extr_file = do
  let extr_n = (length ".extract")
      extr_path = take ((length extr_file) - extr_n) extr_file
      info_file = extr_path ++ ".info"
  -- Extract the file, in CSV format.
  -- URL::|a::|b::|blockquote::|div::|h1::|h2::|i::|img::|p::|span::|strong::|table
  csvtry <- try $ readFile info_file
  -- Handler error
  info <- case csvtry of
            Left _ -> return defaultPageFieldInfo
            Right csv -> do let csv_lst = splitRegex (mkRegex "\\s*[::|]+\\s*") csv
                            return PageURLFieldInfo {
                                           linkUrlField = csv_lst !! 0,
                                           aUrlField = read (csv_lst !! 1) :: Integer,
                                           blockquoteUrlField = read (csv_lst !! 2) :: Integer,
                                           divUrlField = read (csv_lst !! 3) :: Integer,
                                           h1UrlField = read (csv_lst !! 4) :: Integer,
                                           imgUrlField = read (csv_lst !! 5) :: Integer,
                                           pUrlField = read (csv_lst !! 6) :: Integer,
                                           strongUrlField = read (csv_lst !! 7) :: Integer,
                                           tableUrlField = read (csv_lst !! 8) :: Integer
                                       }
  return info
-- End of File

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