src/task2/task2.hs

   1 import Data.List (foldl')
   2
   3 main :: IO ()
   4 main = do
   5         record_text <- readFile "data/02-rainfall.txt"
   6         let records = readRecords record_text
   7         print $ part1 records
   8         print $ part2 records
   9         print $ part2a records
  10
  11 readRecords :: String -> [Int]
  12 readRecords = takeWhile (< 9999) . map read . lines
  13
  14 part1 :: [Int] -> Int
  15 part1 = length
  16
  17 part2 :: [Int] -> Int
  18 part2 records = round $ ((fromIntegral $ sum records) :: Double)
  19                       / (fromIntegral $ length records)
  20
  21
  22 -- Doing part 2 as a fold, so only traverse the list once
  23 part2a :: [Int] -> Int
  24 part2a records = round $ ((fromIntegral sumR) :: Double) / (fromIntegral count)
  25     where
  26         (sumR, count) = foldl' (\(s, n) r -> (s+r, n+1)) (0, 0) records