Create a 'key remover' function which can process any generic object

0:00 Generics are really interesting in that they're tied to a function's execution context. What that means is that you can make a function, which has one generic locked inside of it, then make another function in the future out of that function with the first generic still locked and add another one.

0:16 Here's what I mean by that. Here, we want to make a function called Make Key Remover. Now, Make Key Remover, what it's going to return is a function to remove keys from an object. Here, the expected case for this object is that it's going to be a new object with just the key of C. Here, we're making a function. Here, we're actually calling the function and using it.

0:38 How do we get around to that? First of all, what we're going to do is we're going to say, "Key, extend string here." This is the first function, the key remover one. We're going to say, This key is a...or key array." This is an array of keys. You can see now that the key's generic has been locked in as A or B.

1:01 What we want to do next is we want to take in the object, which is going to be...I'm going to give it a generic of obj. Obj is going to be here. I'll just save it to get the formatting. Obj, as you can see here, it's been locked in. The generic is locked in here into the key remover. That means that we need to just remove the keys from the object.

1:23 We're going to return from this function. I think it's Omit, and then obj, and then key. If I just return this, I need to quieten down the error. What's going on here is that now we've got Omit, which removes keys from an object.

1:41 We're removing A and B. You can see that the key remover locks in that first generic, which is just up here. Then this one, when we actually instantiate the second function, is, it locks in this generic. The new object, it only has C available to it. Pretty cool.