gistfile1.swift

var x: Int? = 0

// Lets me unwrap x and also check a condition on it
func fooGuard() {
    guard let x = x where x > 0 else {
        return
    }
    
    // Do stuff with x
    x.value
}

// I have to check it exists and force unwrap to check the condition.
// I also need to check the bad case rather than checking that its the good case.
// `x! <= 0` rather than `x! >= 0`
func fooManualCheck() {
    if x == nil || x! <= 0 {
        return
    }
    
    // Do stuff with x
    x!.value
}

// I am not doing early exiting here, but rather the bulk of code is done in the binding
func fooBinding() {
    if let x = x where x > 0 {
        // Do stuff with x
        x.value
    }
    
    return
}

let y = 23

func fooNonOptional() {
    guard y > 0 else {
        return
    }
    
    //Do whatever you want with y since its valid
}

func fooNonOptional2() {
    if y <= 0 {
        return
    }
    
    //Do whatever you want with y since its valid
}