将Ocaml / Haskell类型定义转换为Haskell：*在定义中

Question

尝试将类型定义从Ocaml / F＃转换为Haskell，收到错误：

error: parse error on input `*'

我怎样才能更正代码？

当前 Haskell 代码：

data Func sa sb =
    Empty
    | Leaf Int * (sa * sb) List
    | Branch Int * Int * (Func sa sb) * (Func sa sb)

ocaml的：

type ('a,'b)func =
Empty
| Leaf of int * ('a*'b)list
| Branch of int * int * ('a,'b)func * ('a,'b)func;;

F＃

type func<'a,'b> =
    | Empty
    | Leaf of int * ('a * 'b) list
    | Branch of int * int * func<'a,'b> * func<'a,'b>

Answer 1

data Func a b
    = Empty
    | Leaf Int [(a, b)]
    | Branch Int Int (Func a b) (Func a b)