haskell 的一些教学可以参考： https://www.seas.upenn.edu/~cis194/fall16/index.html CodeWorld：可以在线运行hs代码，基于ghc.js，四舍五入还是在本地跑 https://code.world/haskell 下面是利用 CodeWorld 画圆的小例子 1 2 3 4 5 import CodeWorld main :: IO() main = do drawingOf $ circle 1 ...
运算符函数 (!!) 取第n个元素 1 2 3 4 5 6 7 Prelude> :t (!!) (!!) :: [a] -> Int -> a Prelude> [0,1,2,3,4]!!3 3 Prelude> [0,1,2,3,4]!!0 0 乘方 (^), (^^),(**) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Prelude> :t (^) (^) :: (Integral b, Num a) => a -> b -> a Prelude> 54.5^5 4.8081998590625e8 Prelude> :t (^^) (^^) :: (Fractional a, Integral b) => a -> b -> a Prelude> 5.6^^6 30840.979455999986 Prelude> :t (**) (**) :: Floating a => a -> a -> a Prelude> 0.2**0.1 0.8513399225207846 ...