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I don't understand what purpose the "guard let x = x where x > 0 else {}" achieves for the compiler. Couldn't it have been designed to be "guard x > 0 else {}" and achieve the same goal?

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In this case, x is an optional, eg. Int? (if you are unfamiliar with Swift, this means either an Integer or the special value nil)

"guard let x = x where x > 0 else {}" first unwraps the optional (check if it is not nil), then it checks if the value is greater than 0.

This is the nice thing about "guard let ...". Below the guard statement, x is no longer an optional.

Ah, that makes sense. Thanks!

Also, the code inside the else{} block is required to leave the current scope (e.g. return from the method, fatalError(), assert(false), etc.). In that way, 'x' will always contain a valid value after the guard statement, or statements after the guard statements will not execute.

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