day01.md

Day 1's are usually pretty good for Haskell's stream processing, and this is no exception :)

To get the list of elf calories, we split on the double newlines, and take the sum of the lines of each group.

import Data.List.Split (splitOn)

getCalories :: String -> [Int]
getCalories = map (sum . map read . lines) . splitOn "\n\n"

For part 1, this involves just finding the maximum.

part1 :: String -> Int
part1 = maximum . getCalories

For part 2, we find the sum of the top 3 values:

part2 :: String -> Int
part2 = sum . take 3 . reverse . sort . getCalories