手写compose和pipe函数组合
请手写实现函数组合compose(从右到左)和pipe(从左到右)，并说明与函数柯里化的配合使用。
回答
屠龙少年
function compose(...fns) {
if (fns.length === 0) return arg => arg;
if (fns.length === 1) return fns[0];
return fns.reduceRight((prev, next) => (...args) => next(prev(...args)));
}
function pipe(...fns) {
if (fns.length === 0) return arg => arg;
if (fns.length === 1) return fns[0];
return fns.reduce((prev, next) => (...args) => next(prev(...args)));
}
const add1 = x => x + 1;
const double = x => x * 2;
const minus1 = x => x - 1;
const composed = compose(minus1, double, add1);
console.log(composed(5));
const piped = pipe(add1, double, minus1);
console.log(piped(5));
核心：compose = Redux middleware链；pipe = RxJS pipe操作符。