النمط الخالي من الوسائط

ما أسلوب Point-free

function double(n) { return n * 2; }
const nums = [1, 2, 3];
// pointed: argument named explicitly
console.log(nums.map((n) => double(n))); // [2, 4, 6]
// point-free: no named argument
console.log(nums.map(double));            // [2, 4, 6]

تمرير الدوال مباشرةً

const len = (s) => s.length;
const words = ["a", "bb", "ccc"];
console.log(words.map((w) => w.length)); // pointed: [1, 2, 3]
console.log(words.map(len));             // point-free: [1, 2, 3]

تركيب الدوال

const compose = (f, g) => (x) => f(g(x));
const inc = (n) => n + 1;
const double = (n) => n * 2;
const incThenDouble = compose(double, inc);
console.log(incThenDouble(3)); // (3+1)*2 = 8

دالة مساعدة باسم pipe

const pipe = (...fns) => (x) => fns.reduce((acc, f) => f(acc), x);
const inc = (n) => n + 1;
const double = (n) => n * 2;
const f = pipe(inc, double);
console.log(f(3)); // 8

بناء خطوط المعالجة

const pipe = (...fns) => (x) => fns.reduce((a, f) => f(a), x);
const trim = (s) => s.trim();
const lower = (s) => s.toLowerCase();
const clean = pipe(trim, lower);
console.log(clean("  HELLO  ")); // "hello"

يتيح Currying أسلوب Point-free

const multiply = (a) => (b) => a * b;
const triple = multiply(3);
console.log([1, 2, 3].map(triple)); // [3, 6, 9]

التطبيق الجزئي

const add = (a, b) => a + b;
const add10 = add.bind(null, 10);
console.log([1, 2, 3].map(add10)); // [11, 12, 13]

تركيب الدوال الشرطية

const isEven = (n) => n % 2 === 0;
const negate = (fn) => (x) => !fn(x);
const isOdd = negate(isEven);
console.log([1, 2, 3, 4].filter(isOdd)); // [1, 3]

مقايضات قابلية القراءة

const names = ["ada", "bob"];
console.log(names.map((n) => n.toUpperCase())); // ["ADA","BOB"]

مشكلة مرجع الأسلوب

const calc = {
  factor: 2,
  scale(n) { return n * this.factor; }
};
console.log([1, 2].map(calc.scale.bind(calc))); // [2, 4]

تركيب تحويلات واقعية

const pipe = (...fns) => (x) => fns.reduce((a, f) => f(a), x);
const toNums = (arr) => arr.map(Number);
const onlyPos = (arr) => arr.filter((n) => n > 0);
const sum = (arr) => arr.reduce((a, n) => a + n, 0);
const process = pipe(toNums, onlyPos, sum);
console.log(process(["3", "-1", "4"])); // 7

تحقق سريع

مراجعة