[TOC] ## compose 將多個函數合并成一個函數，**從右到左執行**。 ``` R.compose(Math.abs, R.add(1), R.multiply(2))(-4) // 7 ``` ## pipe 將多個函數合并成一個函數，從左到右執行 ``` var negative = x => -1 * x; var increaseOne = x => x + 1; var f = R.pipe(Math.pow, negative, increaseOne); f(3, 4) // -80 => -(3^4) + 1 ``` ## curry 將多參數的函數，轉換成單參數的形式 ``` var addFourNumbers = (a, b, c, d) => a + b + c + d; var curriedAddFourNumbers = R.curry(addFourNumbers); var f = curriedAddFourNumbers(1, 2); var g = f(3); g(4) // 10 ``` ## memoize 返回一個函數，會緩存每一次的運行結果 ``` var productOfArr = arr => { var product = 1; arr.forEach(i => product *= i); return product; }; var count = 0; var factorial = R.memoize(n => { count += 1; return productOfArr(R.range(1, n + 1)); }); factorial(5) // 120 factorial(5) // 120 factorial(5) // 120 count // 1 ``` ## zipWith ``` var f = (x, y) => { // ... }; R.zipWith(f, [1, 2, 3])(['a', 'b', 'c']) // [f(1, 'a'), f(2, 'b'), f(3, 'c')] ```