Tia  Gottlieb

Tia Gottlieb

1595831640

Functional Programming: Higher Order Functions

A Better Take on JavaScript’s Higher Order Functions.

Image for post

Functional Programming is awesome! It makes programming fun.

Learning to program “functionally” is going to make you a fantastic programmer and you will feel secure with the quality of your work.

Image for post

You will be able to write your programs with fewer bugs and in less time because you will be able to re-use your code.

Within this paradigm, we will focus on one of the most important concepts in functional programming, and that is Higher-Order Functions.


So let’s get started!

In JavaScript, and in many functional programming languages, functions are values.

Let’s take a simple function for example:

function double(x) {
  return x * 2
}

What is super cool about JavaScript is that we can take this function and make it into an anonymous function to pass it around and re-use it by declaring a variable.

let double = function(x) {
    return x * 2
 }

let pancake = double 
pancake(40) // 80

We declared a variable _double _and assigned it to the anonymous function. Then we declared another variable, pancake, and assign it to the same function. Just like strings and numbers, functions too can be assigned to variables.

So, in functional programming, functions are values and they can be assigned to variables and they can also be passed into other functions.

Functions that operate on other functions, either by taking them as arguments or by returning them, are called higher-order functions. — see Eloquent JavaScript

In other words, as pertaining to our example, higher-order functions can be understood as functions being passed into other functions to do awesome things!!!

Sure, that makes sense, right? But what are these good for?

Composition.

The fact that we can take one function and put it into another function allows us to compose a lot of small functions into bigger functions.

Let’s look at how to use one of these higher-order functions. Probably the most basic and useful function is

Filter( )

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Image for post

Filter() is a function on the array that accepts another function as its argument, which it will use to return a new filtered version of the array.

Let’s make a fun array of something.

const pets = [

  { name: 'Flip flop', species: 'rabbit' },
  { name: 'Dino', species: 'dog' },
  { name: 'Ralph', species: 'fish' },
  { name: 'Chuchi', species: 'cat' },
  { name: 'Ari', species: 'dog' },
  { name: 'Spock', species: 'dog' },
  { name: 'ying yang', species: 'cat' },
]

What we want to do here is to just “filter” out all the dogs.

Our output must include Dino, Ari, and Spock. 😆

Question: How would I do this with a normal loop?

#higher-order-function #javascript #security #programming #code-review #function

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Functional Programming: Higher Order Functions
Tia  Gottlieb

Tia Gottlieb

1595831640

Functional Programming: Higher Order Functions

A Better Take on JavaScript’s Higher Order Functions.

Image for post

Functional Programming is awesome! It makes programming fun.

Learning to program “functionally” is going to make you a fantastic programmer and you will feel secure with the quality of your work.

Image for post

You will be able to write your programs with fewer bugs and in less time because you will be able to re-use your code.

Within this paradigm, we will focus on one of the most important concepts in functional programming, and that is Higher-Order Functions.


So let’s get started!

In JavaScript, and in many functional programming languages, functions are values.

Let’s take a simple function for example:

function double(x) {
  return x * 2
}

What is super cool about JavaScript is that we can take this function and make it into an anonymous function to pass it around and re-use it by declaring a variable.

let double = function(x) {
    return x * 2
 }

let pancake = double 
pancake(40) // 80

We declared a variable _double _and assigned it to the anonymous function. Then we declared another variable, pancake, and assign it to the same function. Just like strings and numbers, functions too can be assigned to variables.

So, in functional programming, functions are values and they can be assigned to variables and they can also be passed into other functions.

Functions that operate on other functions, either by taking them as arguments or by returning them, are called higher-order functions. — see Eloquent JavaScript

In other words, as pertaining to our example, higher-order functions can be understood as functions being passed into other functions to do awesome things!!!

Sure, that makes sense, right? But what are these good for?

Composition.

The fact that we can take one function and put it into another function allows us to compose a lot of small functions into bigger functions.

Let’s look at how to use one of these higher-order functions. Probably the most basic and useful function is

Filter( )

Image for post

Image for post

Filter() is a function on the array that accepts another function as its argument, which it will use to return a new filtered version of the array.

Let’s make a fun array of something.

const pets = [

  { name: 'Flip flop', species: 'rabbit' },
  { name: 'Dino', species: 'dog' },
  { name: 'Ralph', species: 'fish' },
  { name: 'Chuchi', species: 'cat' },
  { name: 'Ari', species: 'dog' },
  { name: 'Spock', species: 'dog' },
  { name: 'ying yang', species: 'cat' },
]

What we want to do here is to just “filter” out all the dogs.

Our output must include Dino, Ari, and Spock. 😆

Question: How would I do this with a normal loop?

#higher-order-function #javascript #security #programming #code-review #function

Higher-Order Functions Beginners Should Be Familiar With.

Higher-order functions are functions that operate on other functions, either by taking them as arguments or by returning them.

There are a lot more higher order functions than what will be covered in this article, but these are good ones to get you up and running as a beginner. These standard array methods are forEach() , filter() , map() and sort() .

  1. **forEach( ): **This is used when you want to operate on or interact with any element inside of an array. Basically works like the_ for loop._

N.B- I’d be using examples to illustrate each method so you can get a clearer picture, and also just printing to the console to keep the examples as simple and basic as possible.

Example: Lets say in an array of a group or friends, and we want to loop through that array and print to the console each element of that array.

Using a for loop ;

const friends = ['Toyin', 'Olumide', 'Fola', 'Tola'];

for ( let i=0; i < friends.length ; i++) {
  cosole.log (friends[i])
};

The action same as above can be achieved using theforEach() method as seen below;

const friends =  ['Toyin', 'Olumide', 'Fola', 'Tola'];

friends.forEach(function(name) {
  console.log(name)
};

What the forEach() method simply does is to take in a function as an argument and loop through each item in the array without using iteration[i].

This is really awesome when the ES6 arrow functions are used, our code is reduced to a single line that is clean and maintainable. As seen below:

const friends =  ['Toyin', 'Olumide', 'Fola', 'Tola'];

friends.forEach(name => console.log (name));

2. **_filter( ) : _**Just like the name implies, it is used to filter out elements of an array that do not meet the conditions set in the callback function passed as an argument. The callback function passed to the filter() method accepts 3 parameters: elementindex, and array , but most times only the element parameter is used.

**Example : **In an array showing a group of friends and their ages, lets say we want to print to the console the friends that can drink assuming the age limit for drinking is 18. Using a for loop without high order functions;

const friends = [
  {name : 'Toyin', age: 24},
  {name : 'Olumide', age: 14},
  {name : 'Fola', age: 12},
  {name : 'David', age: 42}
];
for ( let i=0 ; i<friends.length ; i++) {
   if (friends[i].age > 18) {
    console.log(`${friends[i].name} can drink`);
 }
};

Now using the filter() method :

const friends = [
  {name : 'Toyin', age: 24},
  {name : 'Olumide', age: 14},
  {name : 'Fola', age: 12},
  {name : 'David', age: 42}
];
friends.filter (function (friend) {
  if (friend.age > 18){
   return true;
 } 
});

#functional-programming #beginners-guide #javascript #higher-order-function #es5-vs-es6 #function

Tanya  Shields

Tanya Shields

1597703580

Higher-Order Functions Explained

Whether you are a beginner or a 10x developer, chances are that you have used the methods of the Array Object. The methods in the Array Object are classified into two different categories. One category takes a value as arguments( string, integer, array, object) and another category takes a function as arguments.

In this article, we are going to focus on the second categories of methods called, higher-order functions and look at their implementation.

Before we dive into what higher-order functions are and what we can do with them, let’s look at the reasons why we need functions in general.

Why functions?

We all agree that a program that is large in size is easily error-prone and the error is difficult to detect, hence reducing the size of the program without altering the way it works will be the ideal solution. Using functions make a program more likely to contain a bug. For example, the following code is intended to filter an array to get all the values lower than a specified predicate.

let arr= [23, 43, 12, 43, 54, 34];
let result = [];
for (let i = 0; i < arr.length; i++) {
    if (arr[i] < 40) {
      result.push(arr[i])
    }
  }
console.log(result)

However the same could be achieved with a higher-order function using just one line of code.

console.log([23,43,12,43,54,34].filter(i=>i<40))

Don’t get me wrong, the filter method on the array object may be larger in size than our implementation but that’s the goal of a function, to provide us with an abstraction.

Function, allows solutions to be expressed in the vocabulary that corresponds to the problem being solved and are reusable, therefore, prevent repetitive code.

#javascript #functional-programming #high-order-functions #programming #software-development

Angela  Dickens

Angela Dickens

1595593200

Functional Programming

Functional Programming is a Declarative style of Programming Paradigm for writing computer programs.
But, What are Functions ?
Functions in general, applies computation on given input and returns the output. It relates input to an output.
f(x) = x + 2;
f(1) = 1 + 2 = 3;
f(2) = 2 + 2 = 4;
Above mentioned is a simple function that adds 2 to the input value and returns output. It relates value [1,2] => [3,4]. Similarly, a function in computer programming is a block of instruction that performs computation on given input and returns the output.
Functional Programming is such a style of writing computer programs using these tiny functions that works together and perform required computation.
Functions in Functional Programming
The philosophy of functional programming is to maintain certain characteristics while writing functions in a computer program. These characteristics are the fundamental nature of functional programming that describe what shall be the behaviour of a function. These are as follows :
Declarative
A function must be declarative, it simply tells what to compute, without specifying how to compute it.
f(x) = x * 4; 👍
Declarative function that tells to multiply input by 4;
f(x) = { y = x + x; z = x + x; return y + z;} 👎
Non-Declarative function that specify how to multiply input by 4;
Pure
A function must give the same output for a given input value, at any period of time. It is not dependent upon anything outside the function definition.
f(x) = It’s never too late; 👍
Pure function that will always return It’s never too late
f(x) = If today’s Friday or Saturday then It’s never too late else It’s late. 👎
Impure function that consider day for returning value. The value is not predictable. It can change. So a function that performs anything which is unpredictable is not a pure function. The condition or the execution is dynamic or unfixed in an impure function.

#development #functional-programming #software #software-programming #declarative-programming #function

What are Higher-Order Functions?

Are you already using them?

Though the term higher-order may sound fancy and complicated, it is actually much simpler than you’d think. In fact, you have probably already used higher-order functions without even realizing it.

higher-order function is a function that either takes a function or functions in as an argument or returns a function. All other types of functions are considered first-order functions. Because JavaScript accepts higher-order functions, that is what makes this programming language suitable for functional programming.

To better understand this concept, you first need to know a bit about functional programming and first class functions. Functional programming is a paradigm where you build applications with functions, as the name implies. This is accomplished with the use of pure functions, recursion and avoiding side-effects, mutable data, and shared state. If you want a more thorough explanation on functional programming, you can read my post about it here.

#javascript #functional-programming #higher-order-function