Question

我正在使用OCaml v 4.00.1。我试图使用相互递归编写一个函数来获取一个列表并返回一个int。 int是获取列表的交替元素并相互相加和相减的结果。例如，列表[1; 2; 3; 4]将导致1 + 2 - 3 + 4 = 4.

我的代码如下：

let alt list =
  let rec add xs = match xs with 
    [] -> 0 
    | x::xs -> x + (sub xs)
  and sub xs = match xs with 
    [] -> 0
    | x::xs -> x - (add xs);;

OCaml在;;上抛出语法错误在代码的最后。我不确定从哪里开始弄清楚这个错误究竟是什么。

Answer 1

我怀疑您忘记添加let alt list = let rec add xs = match xs with | [] -> 0 | x::xs -> x + (sub xs) and sub xs = match xs with | [] -> 0 | x::xs -> x - (add xs) in add list绑定的+部分 - 粗体

中的更改

这将以... in sub list开始序列，即1 + 2 - 3 ...

如果您希望它以match ...

开头

function

我们可以为let alt list = let rec add = function | [] -> 0 | x::xs -> x + (sub xs) and sub = function | [] -> 0 | x::xs -> x - (add xs) in add list交换printAccountSummary: function() {return "Welcome!" + "\n" + "Your balance is currently $1000 and your interest rate is 1%."} }; console.log(savingsAccount.printAccountSummary()); // method语法，并在此处改进了可读性

Welcome!
Your balance is currently $1000 and your interest rate is 1%.

OCaml中列表上的相互递归语法错误

1 个答案: