有没有办法在 OCaml 中进行 C 风格的前向声明？
我的问题是我有两个相互引用的变体：
type path_formula =
[ `Next of state_formula
| `Until of (state_formula * state_formula)
| `UntilB of (state_formula * int * state_formula)
]
type state_formula =
[ `True | `False
| `Not of state_formula
| `And of (state_formula * state_formula)
| `Or of (state_formula * state_formula)
| `Imply of (state_formula * state_formula)
| `Label of string
| `Prob` of (boundf * path_formula)
| `Expc` of (boundi * formula)
]
所以这两种类型都必须知道另一种。我在谷歌上搜索过，但不幸的是 OCaml 不是一种如此广泛使用的编程语言。