Original subtitles

‫A declarative language, what are we talking about?

‫I can already hear you saying the what?

‫Well, to put it into simple terms, a declarative language is a language where we say, what will happen?

‫OK, I can see the gears spinning.

‫Right.

‫What will happen when we look at our school query?

‫We said select star from users.

‫We know we want to get data back.

‫We're saying what will happen?

‫Select star from users.

‫You're going to get feedback from users, but we have no idea how that's going to happen.

‫That's why we call it declarative.

‫We are simply stating something that is going to have on the counter end of that, we have what we call

‫imperative programming and imperative programming says how it will happen.

‫So what do we mean by that?

‫We just define that declarative, declarative meaning.

‫We see what will happen, but we have no idea how it's happening.

‫And on the other end, the imperative is saying how it will happen.

‫Imperative programming is where you go line by line by line, saying do this, do that, do that, go

‫read from over there in declarative.

‫You just say, give me this.

‫Let's break that down a bit more.

‫If we were to look at this, the man asking for a ham sandwich and getting one without having to do

‫anything, well, that's equivalent to declarative programming, right?

‫You say I want something.

‫This is what I want back.

‫This is what should happen.

‫And you get it back and however it happens is irrelevant to you.

‫It happens in a black box.

‫It happens somewhere behind the scenes.

‫And you don't know anything about what goes on there in an imperative programming.

‫You are the bandleader.

‫You are the one saying, let's do this, then let's do that, and then we will have an outcome.

‫So in the case of a ham sandwich, you are the one saying sliced the bread, slice the ham and putting

‫together the sandwich.

‫And if we were to look at some examples of declarative versus imperative programming, what we would

‫look at is, for instance, school.

‫Right.

‫We've already defined that.

‫That's on the declarative and select star from users.

‫Very clear, very straightforward.

‫You know that you're going to get user data back.

‫And Java, an old programming language that is still relevant today that some of you may have heard

‫of is a programming language where traditionally you would define everything that needs to happen.

‫You would define where you need to read from a hard drive where all of the data is.

‫And you would do all of the actions to get the data on the opposite end.

‫Something like Python can be both declarative and imperative.

‫You can do both with it.

‫We've created this clear divide and we've seen what declarative can do versus what imperative can do,

‫and it's more simple than it looks, right?

‫Declarative is very powerful because of its simplicity, because you don't have to worry about what's

‫going to happen behind the scenes.

‫And you can just say, hey, get me this, hey, get me that.

‫You can be more productive versus imperative.

‫You have more flexibility.

‫You have more power.

‫You can do way more things.

‫But it becomes more complicated as you go along because you have to manage all of these extra things.