带有 Core_unix.exec 的 OCaml Core_unix.fork 永远不会返回

Question

由于子进程返回 Core_kernel.Std.never_returns，我在以下列方式执行 fork 时遇到问题并且 parent 正在尝试返回 () .

我收到错误 This expression has type unit but an expression was expected of type Core_kernel.Std.never_returns = Core_kernel.Nothing0.t .似乎无法通过 Core.Std 找到正确的方法来执行此操作.

open Core.Std
open Unix

let () = 
  let prog = "ls" in
  let args = ["ls"; "-l"] in
  match Unix.fork () with
  | `In_the_child ->
     Unix.exec ~prog:prog ~args:args ();
  | `In_the_parent _ ->
     (* continue on with the program *)

Answer 1

never_returns type 专门设计用于与 never_returns 一起食用功能。这是要求程序员在代码中明确说明，他理解表达式不会终止。这是一个工作示例:

let () =
  let prog = "ls" in
  let args = ["ls"; "-l"] in
  match Unix.fork () with
  | `In_the_child ->
    Unix.exec ~prog ~args () |>
    never_returns
  | `In_the_parent _ -> ()