gistfile1.hs

import Text.ParserCombinators.Parsec

data RailsLogHeaderLine = RailsLogHeaderLine {
  requestMethod       ::  String,
  requestAction       ::  String,
  requestIp           ::  String,
  requestTime         ::  (String, String) 
} deriving (Show, Ord, Eq)

data RailsLogSummaryLine = RailsLogSummaryLine {
  requestStatus       ::  String,
  requestTotalTime    ::  String,
  requestViewTime     ::  String,
  requestDbTime       ::  String
} deriving (Show, Ord, Eq)

data RailsLogParsingResult = Fail String
  | Header RailsLogHeaderLine
  | Summary RailsLogSummaryLine

plainValue :: Parser String
plainValue = many1 (noneOf " ")

headerLogLine :: Parser RailsLogHeaderLine
headerLogLine = do
  plainValue
  space
  method <- plainValue
  space
  action <- plainValue
  space
  plainValue
  space
  host <- plainValue
  space
  plainValue
  space
  date <- plainValue
  space
  hour <- plainValue
  space
  hour_offset <- plainValue
  return $ RailsLogHeaderLine method action host (date, hour)

--summaryLogLine :: Parser RailsLogSummaryLine
--summaryLogLine = do
--  plainValue
--  space
--  status <- plainValue
--  space 
--  plainValue
--  space
--  plainValue
--  space
--  totalTime <- plainValue
--  space
--  return $ RailsLogSummaryLine status totalTime

parseLine inputLine = case  parse headerLogLine "(test)" inputLine of
    Left  err -> Fail $ show err
    Right res -> Header res  

clearFailedParses [] = []
clearFailedParses (h:hs) = 
  case h of
    Header hdr -> show hdr
    Fail err -> clearFailedParses hs

main = do 
  file <- readFile "production.log"
  let logLines = lines file in
    let parseResult = map parseLine logLines in
      let results = clearFailedParses parseResult in
        print results