So you can update your article to mention `listOf 1 2 3 filterIsInstance lt String gt first ` which gives you `String` value

Anything wrong about them slightly smiling face

You might want to ask in < C0BUHC9HD|kontributors>

This was my extension solution ```fun lt T U T gt Observable lt T gt filterMap cls Class lt U gt Observable lt U gt return filter cls isInstance it map cls cast it ```

So you can update your article to mention `listOf 1 2 3 filt kotlinlang #announcements

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Title

orangy

02/08/2017, 10:25 AM

So you can update your article to mention

listOf(1, “2”, 3).filterIsInstance<String>().first()

which gives you

String

value

👍 1

dawidhyzy

02/08/2017, 11:34 AM

orangy: how about first/firstOrNull ?

orangy

02/08/2017, 11:35 AM

Anything wrong about them? 🙂

dawidhyzy

02/08/2017, 11:36 AM

nothing but is there easy way to find first and cast?

bob

02/08/2017, 12:58 PM

Post updated, but I still would love smart cast throughout the language 😎

orangy

02/08/2017, 1:02 PM

Smart casts are everywhere, where it is possible for compiler to infer them. In an arbitrary function receiving a lambda it cannot deduce it. Well, it could in some cases, if it could see through inline lambda, but not for collections.

bob

02/08/2017, 5:24 PM

Yeah but you can still dream 😃 Btw awesome response here! Love it! Is there anywhere a kotlin-developer like myself can contribute to the language or community? Where would you recommend that to be?

orangy

02/08/2017, 5:35 PM

You might want to ask in #kontributors

Also check http://kotlinlang.org/contribute.html

bob

02/08/2017, 6:53 PM

Cool, I’ll do that. I also first solved my problem with Rx with an extension function in kotlin combining

filter

and

map

. And than I found that Rx actually has a filter function for it as well:

ofType

This was my extension solution:

fun <T,U:T> Observable<T>.filterMap( cls:Class<U> ):Observable<U> { 
  return filter { cls.isInstance( it ) }
           .map { cls.cast( it ) }
}

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