Check if `t` is `Iterable` inside your `concat`, a...

# announcements

[edwardwongtl]

Check if t is Iterable inside your concat, and skip the listOf(t) is true

[karelpeeters]

Yikes, I'd just create a new function at this point.

[nil2l]

But… it all looks strange and buggy. In Kotlin I mean.

[karelpeeters]

Just go with the infix one.

[nil2l]

With concat same thing. So it’s not a problem of plus operator.

[karelpeeters]

Right, but the problem is that + is defined to combine two lists by the stdlib, so basically you're breaking it.

[nil2l]

Well… if you write 1 + listOf(2) you receive undefined. So what does it break?

[karelpeeters]

The problem is that you break listOf(1) + listOf(2) as well.

[nil2l]

Yes. I think it’s a bug in kotlin. Because List< T> != T.

[nil2l]

For example if you define concat with Int instead of generic T it won’t break concat of two lists, it will say type error. And it’s correct.

[edwardwongtl]

I don't think its a bug, T is just a over generalised type, if you don't give any bound to it, it can be anything

[karelpeeters]

Well no, the compiler just picks T = Any and then they both match.

[edwardwongtl]

Make your T more specific to the type your want to affect

[nil2l]

Ok. How should I define T to succeed List< T> != T?

[edwardwongtl]

Maybe T: List<*>?

[karelpeeters]

Well that's the point, it should work for everything but Iterable, and I don't think that's possible.

[nil2l]

Also Collection defines a plus operator. But as I said it’s not only a problem of plus operator.

[nil2l]

I’ll try more later. Thanks for suggestions. 🙂

[karelpeeters]

Collection defines a more specific method that can be more performant than the iterator one in some cases, but that's not a problem because the bahavior is exactly the same.