Swift 'if let' statement equivalent in Kotlin

Question

In Kotlin is there an equivalent to the Swift code below?

if let a = b.val {

} else {

}

Answer 1

Let's first ensure we understand the semantics of the provided Swift idiom:

if let a =  {
     // then-block
}
else {
     // else-block
}

It means this: "if the results in a non-nil optional, enter the then-block with the symbol a bound to the unwrapped value. Otherwise enter the else block.

Especially note that a is bound only within the then-block. In Kotlin you can easily get this by calling

?.also { a ->
    // then-block
}

and you can add an else-block like this:

?.also { a ->
    // then-block
} ?: run {
    // else-block
}

This results in the same semantics as the Swift idiom.