list - Ocaml列表函数

Question

我对 Ocaml 函数有一些“问题”。

定义 function all_odd，它对于给定的矩阵作为参数检查所有元素是否都是奇数。

val all_odd : int list list -> bool = <fun>

例子：

#let matrix1 = [[1; 2]; [3; 4]];;
val matrix1 : int list list = [[1; 2]; [3; 4]]

#all_odd matrix1;;
- : bool = false;

Answer 1

You can solve that problem in many way, but the best approach would be to decomposite the problem into simple ones.

• Step 1: What's smallest problem to solve? How to check if a number is odd

  x mod 2 != 0

• Step 2: How to use it for a whole list of numbers

  let isOdd list = List.for_all (fun x -> x mod 2 != 0) list

• Step 3: How to use it for a matrix

---

let all_odd matrix =
    let isOdd list = List.for_all (fun x -> x mod 2 != 0) list in
    List.for_all isOdd matrix

Makes sense?