square :: Int -> Int
-- pruning with 14/25 rules
-- 3 candidates of size 1
-- 3 candidates of size 2
-- 6 candidates of size 3
-- tested 9 candidates
square x = x * x
square :: Int -> Int
-- pruning with 14/25 rules
-- 3 candidates of size 1
-- 3 candidates of size 2
-- 6 candidates of size 3
-- tested 9 candidates
square x = x * x
sum :: [Int] -> Int
-- pruning with 4/8 rules
-- 1 candidates of size 1
-- 2 candidates of size 2
-- 2 candidates of size 3
-- 3 candidates of size 4
-- 5 candidates of size 5
-- tested 13 candidates
sum [] = 0
sum (x:xs) = x + sum xs
(++) :: [Int] -> [Int] -> [Int]
-- pruning with 3/3 rules
-- 2 candidates of size 1
-- 4 candidates of size 2
-- 13 candidates of size 3
-- 35 candidates of size 4
-- 113 candidates of size 5
-- 288 candidates of size 6
-- tested 347 candidates
[] ++ xs = xs
(x:xs) ++ ys = x:(xs ++ ys)