day1.hs

prodPairs :: Int -> [Int] -> [(Int,Int)]
prodPairs n xs = [(x,y) | x <- xs, y <- xs, x+y == n]

prodTrips :: Int -> [Int] -> [(Int,Int,Int)]
prodTrips n xs = [(x,y,z) | x <- xs, y <- xs, z <- xs, x+y+z == n]

problem1 = readFile "day1.txt" >>= (putStrLn . show . (\(x,y) -> x*y) . head . (prodPairs 2020) . (map read) . lines)

problem2 = readFile "day1.txt" >>= (putStrLn . show . (\(x,y,z) -> x*y*z) . head . (prodTrips 2020) . (map read) . lines)

main = problem1 >> problem2