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Welcome back.

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And this video we're going to look at lambda expressions and lambda expressions are a pretty cool feature.

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They allow us to write super concise and short code that does quite some advanced things.

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So let's look at that.

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What is a lumba expression?

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A lambda or a lambda expression both as fine as a function which has no name, but I love the expression

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is not the same as an anonymous function, which also has no name so that there's a little distinction

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there.

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We're going to focus on lambda expressions for now, though, because these are the ones that we're

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going to use and that we already have used when we used the click event.

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So lambda expressions and anonymous functions are functional literals, for example, functions that

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are not declared but passed immediately as an expression.

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So lambda is defined with curly braces, which takes variables as a parameter, if any.

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And a body of a function so it can take variables as a parameter, but it doesn't have to.

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OK, so it's not a requirement.

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The body of a function is written after the variable, if any, followed by the Arrow operator.

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So this is the lambda operator, so to speak.

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So this is a dash with an arrow.

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And the syntax is variable or variables, lambda expression, body of lender, and all of that is surrounded

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by curly brackets.

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So let's look at a normal function addition of two numbers where we create a function, add numbers

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or add number passing to arguments and b add number five or 10 are the two values that we pass.

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So A is five and 10, and the function looks like this function.

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Add number A and B, and then we have the value add is a plus B, and then we print this case, just

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add.

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And that's it.

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So this is what our function does very basic.

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Now the thing is we can have this output of 15, but we can really shorten this.

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Now let's see how we can do that with a lambda expression.

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So we will write the same example using lambda expressions.

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So here we have some intent that's going to return.

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So what we're saying is that we are creating a lambda expression called sum, and we take two parameters

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and an int or of type int and we return and enter.

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So what we are now saying that the lambda expression itself should be a.

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Of type int b of type and shall return a plus b.

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OK, so this is what we do here.

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So what this after the lambda expression is what is going to be return because we defined it here?

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OK, but it's possible to do this even shorter.

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Of course, we had this print and there in order to display something.

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So we are calling this some lambda expression.

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We passing the two values and then we're printing it because we also wanted to print the value, right?

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But we can do this even shorter so we can have while some a of Typekit b of type int is already part

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of the lambda expression and then we just print L and a plus B.

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So now if we call some, we pass the two values that will already print fifteen, so it will directly

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print the result.

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So we just had two lines.

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It's not exactly the same as you can see in one of the two examples where actually returning.

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So in this case, we're returning the value first.

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And then we use it in a print line statements in order to print the return statement.

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And then in this case, we directly added to the print line here in order to display whatever is here.

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So if you wanted to return it, then you would get rid of this print line and then to the same print

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line, some as you had here at the top.

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So both versions are fine, but what you cannot do is use print line in here because you're saying that

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you return an integer.

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Okay, so you still have to follow the structure of whatever you're trying to return.

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It has to be returned.

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Okay, so whatever you defining that will be returned in this case, an integer has to be returned here

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as the return statement.

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All right.

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So this is an example of a lambda expression and we're going to use them the expressions.

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But more importantly, we're going to see lambda expressions in action when we work, for example,

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with events such as click events and in other cases as well.

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So it's more important for you to understand that concept behind it and not be surprised when we see

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them, rather than having to use them the expression to yourself all the time because they are a little

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more advanced than the other ways of creating functions.

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So feel free to use either of them.