homework

Exercises/1-power.js

@@ -1,15 +1,15 @@
 'use strict';
 
 // Define function power(exp, n), the same as Math.pow(n, exp)
-// but with reverse order of argumants.
-const power = null;
+// but with reverse order of arguments.
+const power = (exp, n) => Math.pow(n, exp);
 
 // Implement function `square(n)`, which returns square of its argument.
 // The function may or may not reuse function `power`.
-const square = null;
+const square = (n) => power(2, n);
 
 // Implement function `cube(n)` using partial application
-// The function should return cube of argumant (to the power of three).
-const cube = null;
+// The function should return cube of argument (to the power of three).
+const cube = (n) => Math.pow.bind(null, n)(3);
 
 module.exports = { power, square, cube };

Exercises/2-closure.js

@@ -3,13 +3,13 @@
 const coffee = (volume, strength) =>
   `Coffee volume: ${volume}ml, strength: ${strength}`;
 
-const defineCoffeeType = volume => strength => coffee(volume, strength);
+const defineCoffeeType = (volume) => (strength) => coffee(volume, strength);
 
 // Use function defineCoffeeType to define new coffee types.
 // Define coffee type espresso which volume should equal 50ml.
 // Define coffee type americano which volume should equal 150ml.
 
-const espresso = null;
-const americano = null;
+const espresso = defineCoffeeType(50);
+const americano = defineCoffeeType(150);
 
 module.exports = { espresso, americano };

Exercises/3-lambda.js

@@ -6,6 +6,9 @@ const tagged = (pref, str) => `[${pref}] ${str}`;
 // E.g. tagDate('My String') === '[2019-11-14] My String'
 // Use function tagged to implement tagDate.
 
-const tagDate = null;
+const tagDate = (str) => {
+  const today = new Date().toISOString().split('T')[0];
+  return tagged(today, str);
+};
 
 module.exports = { tagDate };

Exercises/4-bind.js

@@ -19,7 +19,7 @@ const H = (exp, ...args) => {
 // Create function `average` that returns arithmetic mean (H₁) of the arguments.
 // Create function `rootMeanSquare` that returns quadratic mean (H₂).
 
-const average = null;
-const rootMeanSquare = null;
+const average = H.bind(null, 1);
+const rootMeanSquare = H.bind(null, 2);
 
 module.exports = { average, rootMeanSquare };

Exercises/5-curry.js

@@ -7,7 +7,14 @@ const checkPin = (...code) => code.join('') === EXPECTED_PIN;
 // Define function curry that accepts the length of the function
 // (amount of function arguments) and the function.
 
-const curry = (length, fn) => (...args) => null;
+const curry = (length, fn) => (char) => {
+  if (length > 1) {
+    const f = fn.bind(null, char);
+    return curry(length - 1, f);
+  } else {
+    return fn(char);
+  }
+};
 
 // Allows to enter pin code by one character,
 // Usage: press('3')('4')('5')('6')

Exercises/6-chaining.js

@@ -10,6 +10,13 @@ const checkPin = (...code) => code.join('') === EXPECTED_PIN;
 //
 // For hint use https://github.com/HowProgrammingWorks/Cheatsheet
 
-const press = null;
+const press = (n) => ({
+  pin: n,
+  press(sym) {
+    this.pin += sym;
+    if (this.pin.length === EXPECTED_PIN.length) return checkPin(this.pin);
+    return this;
+  }
+});
 
 module.exports = { press };