从用法推断类型

Question

假设存在接口RendererPayloadConnection：

interface RendererPayloadConnection<T> {
  payload: Partial<{
    [K in keyof T]: T[K] extends Callback<infer U>
      ? Tuple<U, any>
      : T[K];
  }>
}

type Callback<U> = (v: U) => void;

type Tuple<U, T> = [UnaryFunction<U, T>, (v: T) => void];

interface UnaryFunction<T, R> { (source: T): R; }

使用此接口可能会导致误报：

function map<T, R>(f: (arg: T) => R): UnaryFunction<T, R> {
  throw 'not implemented';
}

class A {
  output: Callback<string>;
}


const connection: RendererPayloadConnection<A> = {
  payload: {
    output: [
      map(v => v.length),
      n => n.length
    ]
  }
};

（长度错误）

可以通过辅助功能“ tuplify”进行修复：

function tuplify<T, U>(mapper: UnaryFunction<T, U>, cb: Callback<U>): Tuple<T, U> {
  return [mapper, cb];
}

const connection: RendererPayloadConnection<A> = {
  payload: {
    output: tuplify(
      map(v => v.length),
      n => n.length
    )
  }
};

如何描述接口RendererPayloadConnection进行正确的类型检查，而无需使用“ tuplify”帮助程序？

Full code