Using return inside a lambda?

You can also replace { trips -> with fun(trips) { to form an anonymous function which can use return normally.

Just use the qualified return syntax: return@fetchUpcomingTrips.

In Kotlin, return inside a lambda means return from the innermost nesting fun (ignoring lambdas), and it is not allowed in lambdas that are not inlined.

The return@label syntax is used to specify the scope to return from. You can use the name of the function the lambda is passed to (fetchUpcomingTrips) as the label:

mainRepo.fetchUpcomingTrips { trips ->
    if (trips.isEmpty()) {
        showEmptyViews()
        return@fetchUpcomingTrips 
    }

    // ...
}

Related:

• Return at labels in the language reference

• Whats does “return@” mean?