I am working through the online materials for CIS 194, a upenn haskell class (not taking the class). This exercise is to parse an error log, and it gives a few function signatures to implement, ending with the very last one whatWentWrong. Please help me make the code more idiomatic, particularly whatWentWrong. My haskell level is: understood LYAH but have not written much code.
{-# OPTIONS_GHC -Wall #-}
module LogAnalysis where
import Log -- https://github.com/dustingetz/sandbox/tree/master/cis194/hw2
parseMessage :: String -> LogMessage
parseMessage s = case words s of
-- I 5053 pci_id: con ing!
("I":t:msg) -> LogMessage Info (read t) (unwords msg)
-- W 3654 e8] PGTT ASF!
("W":t:msg) -> LogMessage Warning (read t) (unwords msg)
-- E 47 1034 'What a pity it
("E":sev:t:msg) -> LogMessage (Error $ read sev) (read t) (unwords msg)
_ -> Unknown s
parse :: String -> [LogMessage]
parse s = map parseMessage $ lines s
insert :: LogMessage -> MessageTree -> MessageTree
insert (Unknown _) node = node
insert m Leaf = Node Leaf m Leaf
insert m@(LogMessage _ t _) (Node l' m'@(LogMessage _ t' _) r')
| t <= t' = Node (insert m l') m' r'
| t > t' = Node l' m' (insert m r')
build :: [LogMessage] -> MessageTree
build ms = foldl (flip insert) Leaf ms
inOrder :: MessageTree -> [LogMessage]
inOrder (Node l m r) = inOrder l ++ [m] ++ inOrder r
inOrder Leaf = []
--fmap ((take 10) . inOrder . build) $ testParse parse 100 "error.log"
whatWentWrong :: [LogMessage] -> [String]
whatWentWrong ms = map (\(LogMessage _ _ s) -> s) $
filter (\(LogMessage msgType _ _) ->
case msgType of
Error sev -> sev >= 50
_ -> False) $
inOrder $ build ms
