OCaml 中的数据类型定义中的方括号 `[` 和 `]` 是什么意思？

Question

I saw the following :

type rlevel = [
| `rlevel
]

but I've never seen this before and the tutorials for ADTs (algebraic data types) are not super helpful nor is the OCaml grammar.

What does this mean?

Answer 1

类型rlevel是多态变体类型 ( https://ocaml.org/manual/polyvariant.html ) 的类型缩写，它只包含一个构造函数`rlevel 。