maybe

iAmAVar?.let{ it+"XXX" } ?: "XXX"

iAmAVar

is a

Foo

, not a

String

though...

sure

imho a bit of an overuse of let here. But... it's opinion.

let is here for nullity-check, that's exactly his goal

No, it's not really.

let

is here for things where you need want to access something exactly once but need that "captured" value multiple times. Example:

val thing = myExpensiveMethod()
// do stuff with thing

Can be rewritten as:

myExpensiveMethod().let { thing -> 
   // do stuff with thing
}

Hmm ok, was not how I understood this, thanks! I'm still a beginner 🙂