What is lexical scoping and how is it used in different programming languages?

What is lexical scoping and how is it used in different programming languages?

Lexical scoping is a method of variable scope resolution where the scope is determined by the physical structure of the code. In languages like JavaScript, variables defined in a function are accessible within that function and any nested functions, but not outside of them.

Can you give me an example of lexical scoping in JavaScript?

Sure! In JavaScript, if you define a variable inside a function, it cannot be accessed outside that function. For example:

function outerFunction() {
    let outerVar = 'I am outside!';
    function innerFunction() {
        console.log(outerVar); // This will log 'I am outside!'
    }
    innerFunction();
}
outerFunction();

How does lexical scoping differ from dynamic scoping?

Lexical scoping determines the scope based on the location of the variable declaration in the source code, while dynamic scoping determines the scope based on the call stack at runtime. This means that in dynamic scoping, a variable can be accessed based on the function call hierarchy, not just where it was defined.

Which other programming languages use lexical scoping?

Many modern programming languages use lexical scoping, including Python, Ruby, and Swift. Each language has its own rules for how scoping works, but the core concept remains similar.