嵌套函数中接口中的泛型

Question

interface Maybe<A> {
  // this works as expected
  a: <B>(a: A, b: Maybe<B>) => Maybe<B>;

//# Maybe#chain :: Maybe a ~> (a -> Maybe b) -> Maybe b
  // this does not
  chain: <B>((a: A) => Maybe<B>) => Maybe<B>;
}

如何在两个＆＃34;级别上表达期望函数和共享类型变量的函数＆＃34;如片段所示？或者TypeScript的类型系统太弱而无法表达它？

Answer 1

哦，我忘了说出一个论点。工作版（注意fn）：

  chain: <B>(fn: (a: A) => Maybe<B>) => Maybe<B>;