add first exercise of lecture 2

1 files changed, 35 insertions, 0 deletions

diff --git a/lec02/LogAnalysis.hs b/lec02/LogAnalysis.hs
new file mode 100644
index 0000000..fc4d3df
--- /dev/null
+++ b/lec02/LogAnalysis.hs
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+{-# OPTIONS_GHC -Wall #-}
+module LogAnalysis where
+
+import Log
+
+-- Exercise 1
+
+nthWord :: Int -> String -> String
+nthWord n = (!! n) . words
+
+firstWord :: String -> String
+firstWord = nthWord 0
+
+nthWordInt :: Int -> String -> Int
+nthWordInt n = read . nthWord n
+
+timeStamp :: String -> Int
+timeStamp s
+    | firstWord s == "E" = nthWordInt 2 s
+    | otherwise = nthWordInt 1 s
+
+restOfMessage :: String -> String
+restOfMessage s
+    | firstWord s == "E" = (unwords . drop 3 . words) s
+    | otherwise = (unwords . drop 2 . words) s
+
+parseMessage :: String -> LogMessage
+parseMessage s
+    | firstWord s == "I" = LogMessage Info (timeStamp s) (restOfMessage s)
+    | firstWord s == "W" = LogMessage Warning (timeStamp s) (restOfMessage s)
+    | firstWord s == "E" = LogMessage (Error (nthWordInt 1 s)) (timeStamp s) (restOfMessage s)
+    | otherwise = Unknown s
+
+parse :: String -> [LogMessage]
+parse = map parseMessage . lines