Implicit type conversion?

Hello,
I’m exploring rescript-react and noticed a peculiar behaviour. Here’s my test code:

module MyComponent = {
  @react.component
  let make = () => {
    let (value, setValue) = React.useState(_ => 0)
    <>
      <div> {React.string(string_of_int(value))} </div>
      <input
        onChange={evt => {
          let x = ReactEvent.Form.target(evt)["value"] // 1
          setValue(_ => x) // 2
        }}
      />
    </>
  }
}

What I noticed is that on the line marked with // 1 the type of x is 'a, but on line // 2 hovering over x shows the type int. Why is that? I would expect the compiler to ask me to decode the value of x.

Thank you in advance!

P.S.

• Playground
• a thread on the forum

从所提供组件中的 ReactEvent.Form.target(evt)["value"] 表达式和 useState setter 开始，然后使用链接的 Playground 重现该行为。将结果与链接的论坛主题进行比较，并确定推断出的类型是否是有意为之；当行为得到澄清或确定了具体的仓库更改时，即视为完成。