如何使用变体选项在脚本中键入函数参数？

Posted 2023-02-16

【中文标题】如何使用变体选项在脚本中键入函数参数？

【英文标题】：How to use a variant option to type function parameters in rescript?

【发布时间】：2021-04-14 08:56:48

【问题描述】：

我想做以下事情。但似乎我无法使用变体选项之一键入函数参数。在脚本中实现这一目标的正确方法是什么？

Here is a playground

  type subject = Math | History

  type person =
    | Teacher(firstName: string, subject: subject)
    | Student(firstName: string)
  
  let hasSameNameThanTeacher = (
    ~teacher: Teacher, // syntax error here
    ~student: Person,
  ) => 
    teacher.firstName == student.firstName
  

【参考方案1】：

Teacher 和 Student 本身不是类型，而是构造 person 类型值的构造函数。如果您希望它们具有不同的类型，则必须明确说明：

module University = 
  type subject = Math | History

  type teacher = firstName: string, subject: subject
  type student = firstName: string
  type person =
    | Teacher(teacher)
    | Student(student)
  
  let hasSameNameThanTeacher = (
    ~teacher: teacher,
    ~student: student,
  ) => 
    teacher.firstName == student.firstName