函数式编程组合技巧详解

const compose = (...fns) => (value) => fns.reduceRight((acc, fn) => fn(acc), value);

// 使用示例

const toUpper = str => str.toUpperCase();

const addExclamation = str => str + '!';

const greet = str => 'Hello, ' + str;

const welcome = compose(toUpper, addExclamation, greet);

welcome('world'); // 输出: HELLO, WORLD!

const pipe = (...fns) => (value) => fns.reduce((acc, fn) => fn(acc), value);

const curry = (fn) => {

  return function curried(...args) {

    if (args.length >= fn.length) {

      return fn.apply(this, args);

    } else {

      return (...nextArgs) => curried(...args, ...nextArgs);

    }

  };

};

// 示例

const add = (a, b, c) => a + b + c;

const curriedAdd = curry(add);

curriedAdd(1)(2)(3); // 6

const addOne = curriedAdd(1);

addOne(2)(3); // 6

const processUser = pipe(

  curriedAdd(1),

  x => x * 2,

  Math.sqrt

);

const Maybe = value => ({

  map: fn => value == null ? Maybe(null) : Maybe(fn(value)),

  getOrElse: defaultValue => value == null ? defaultValue : value

});

// 使用

Maybe('hello')

  .map(s => s.toUpperCase())

  .map(s => s + '!')

  .getOrElse('Empty'); // "HELLO!"