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`.mapNotNull { it.foo }.filter { barFunction(it) }`

this would give me a list of `foo`. I had intended to get a list of elements of `someList`

Can you just merge two `filter`s?
```someList
.filter(it.foo != null &amp;&amp; barFunction(it.foo))```
if `foo` is `val` without custom getter, then this should work

Not sure if I like it better than using a double filter with !!, but I guess it is a bit cleaner

Could you make `barFunction` an extension method on a nullable receiver of the type in your list?

Then you could collapse it to: ```someList
.filter(it.foo.barFunction())```

Or if receiver is not nullable, then
```someList
.filter(it.foo?.barFunction() == true)```

I mean make the extension on a nullable receiver, something like:
```
fun Fun?.barFunction() = this != null &amp;&amp; barFunction(this)
```

Everything is null-safe and the call site is really clean

Except that the behavior wanted on null may be different depending on the caller.

Then that caller can define another extension method

<@UDAH43B0B> good idea! In my case it would not work, unfortunately, as `barFunction` is already a method on a wrapper to a library. I guess my only option left is to overload barFunction on that wrapper

Hey <@UE382L5NX> - I’m not sure if I’m being clear here.  What I mean is in the scope of your filter method, define a _private_ _extension_ method.  The fact it exists on a wrapper is fine!

Aha! Thanks, I did not get that, now I do!

`.filter { foo?.let { barfunction(it) } ?: false }`
would be my sugestion