javascript - pipe() 函数的 typescript 类型

Question

考虑以下 TypeScript 代码:

type operator<T> = (input:T) => T

const pipe = <T>(...operators:operator<T>[]) => (input:T):T => operators.reduce((output, f) => f(output), input)

const add2:operator<number> = x => x+2

const times3:operator<number> = x => x*3

console.log(pipe(add2, times3)(1))    //output 9

管道函数只是将一个运算符的输入通过管道传递给下一个运算符的结果。
现在考虑运算符类型的这个新定义:

type operator<T, U> = (input:T) => U

管道函数应该如何改写为了让 IDE 让我知道我是否正确使用了这些类型？
例如:考虑这两个运算符:

const times3:operator<number, number> = x => x*3

const toStr:operator<number, string> = x => `${x}`

我希望它能够正常工作:

pipe(times3, toStr)(1)

在这里，我希望 IDE 警告我类型错误:

pipe(toStr, times3)(1)

这个我想不通，先谢谢了。

Answer 1

这里是如何 RxJS does it :

pipe(): Observable<T>;
pipe<A>(op1: OperatorFunction<T, A>): Observable<A>;
pipe<A, B>(op1: OperatorFunction<T, A>, op2: OperatorFunction<A, B>): Observable<B>;
pipe<A, B, C>(op1: OperatorFunction<T, A>, op2: OperatorFunction<A, B>, op3: OperatorFunction<B, C>): Observable<C>;
pipe<A, B, C, D>(
    op1: OperatorFunction<T, A>,
    op2: OperatorFunction<A, B>,
    op3: OperatorFunction<B, C>,
    op4: OperatorFunction<C, D>
): Observable<D>;
pipe<A, B, C, D, E>(
    op1: OperatorFunction<T, A>,
    op2: OperatorFunction<A, B>,
    op3: OperatorFunction<B, C>,
    op4: OperatorFunction<C, D>,
    op5: OperatorFunction<D, E>
): Observable<E>;
pipe<A, B, C, D, E, F>(
    op1: OperatorFunction<T, A>,
    op2: OperatorFunction<A, B>,
    op3: OperatorFunction<B, C>,
    op4: OperatorFunction<C, D>,
    op5: OperatorFunction<D, E>,
    op6: OperatorFunction<E, F>
): Observable<F>;
pipe<A, B, C, D, E, F, G>(
    op1: OperatorFunction<T, A>,
    op2: OperatorFunction<A, B>,
    op3: OperatorFunction<B, C>,
    op4: OperatorFunction<C, D>,
    op5: OperatorFunction<D, E>,
    op6: OperatorFunction<E, F>,
    op7: OperatorFunction<F, G>
): Observable<G>;
pipe<A, B, C, D, E, F, G, H>(
    op1: OperatorFunction<T, A>,
    op2: OperatorFunction<A, B>,
    op3: OperatorFunction<B, C>,
    op4: OperatorFunction<C, D>,
    op5: OperatorFunction<D, E>,
    op6: OperatorFunction<E, F>,
    op7: OperatorFunction<F, G>,
    op8: OperatorFunction<G, H>
): Observable<H>;
pipe<A, B, C, D, E, F, G, H, I>(
    op1: OperatorFunction<T, A>,
    op2: OperatorFunction<A, B>,
    op3: OperatorFunction<B, C>,
    op4: OperatorFunction<C, D>,
    op5: OperatorFunction<D, E>,
    op6: OperatorFunction<E, F>,
    op7: OperatorFunction<F, G>,
    op8: OperatorFunction<G, H>,
    op9: OperatorFunction<H, I>
): Observable<I>;
pipe<A, B, C, D, E, F, G, H, I>(
    op1: OperatorFunction<T, A>,
    op2: OperatorFunction<A, B>,
    op3: OperatorFunction<B, C>,
    op4: OperatorFunction<C, D>,
    op5: OperatorFunction<D, E>,
    op6: OperatorFunction<E, F>,
    op7: OperatorFunction<F, G>,
    op8: OperatorFunction<G, H>,
    op9: OperatorFunction<H, I>,
    ...operations: OperatorFunction<any, any>[]
): Observable<unknown>;

它不漂亮，但它完成了工作。