-- -- 定义 sum 函数 -- import Prelude hiding (sum) -- sum :: Int -> Int -> Int -- sum n 1 = n -- sum n m = n + sum (n + 1) (m - 1) -- main :: IO () -- main = print (sum 1 9) -- 主函数，打印结果 fibonacci :: Int -> Int fibonacci 0 = 1 fibonacci 1 = 1 fibonacci n = fibonacci (n - 2) + fibonacci (n - 1) main :: IO () -- main = print (fibonacci n) where n = 10 main = print (fibonacci 10)