=> in Programming

The => symbol, also known as the "goes-to" or "arrow" operator, is commonly used in programming languages to represent a function or operation that maps one value to another.

Syntax

The syntax for => varies between programming languages, but it generally takes the form of:

input => output

or

input => {
    // process input and return output
    return output;
}

Examples

JavaScript

In JavaScript, the => symbol is used to define arrow functions:

// traditional function
function double(x) {
    return x * 2;
}

// arrow function
const double = (x) => {
    return x * 2;
}

// simplified arrow function
const double = x => x * 2;

Ruby

In Ruby, => is used as a hash rocket to assign values to keys in a hash:

person = { name => "Alice", age => 30 }

PHP

In PHP, => is used in associative arrays to assign values to keys:

$person = array("name" => "Alice", "age" => 30);

SQL

In SQL, => is used in the SELECT statement to alias column names:

SELECT first_name => fn, last_name => ln FROM users;

Conclusion

The => symbol is a common shorthand used in many programming languages to represent a function or mapping operation. Whether used as an arrow function in JavaScript, a hash rocket in Ruby, or an alias in SQL, understanding its syntax is an important tool for any programmer.