Do you carry over the Java convention of pre-fixing 'I' for interfaces? Is there an official Kotlin position?

That's by no means an official Java convention. The JDK doesn't do it either.

You should not carry it over, and stop doing it in your Java code too!

Gladly

It's very reminiscent of hungarian notation

Yeah that makes me mCringe too

If you have to preface your interfaces with I, or put Impl on the end of the implementation to differentiate them, then you're not naming things very well. It's very late 1990's coding style for people that thought you HAD to have an interface to do DI, but only had one implementation, and didn't want to think about the actual name for the interface vs the implementation object. And yes, unfortunately, this discussion continues to this day...

mNope

In a different thread. https://kotlinlang.slack.com/archives/C4GKV43N2/p1564059746014200?thread_ts=1564054282.007200&cid=C4GKV43N2

🙇🏻 gotcha that makes sense

But ultimately it comes down to what the team is comfortable with. I've done both, and prefer the 'less work' option when I have to make changes.

As a constructive alternative, I really like using "-ing" "-able" "-er" style suffixes for interface types (or protocols in Swift). So,

HttpFetching

as the interface and

HttpFetcher

as an implementation, for example.

See I would prefer it so that you impl is my interface - so something like

FetchUsers

for the interface and

FetchUsersViaHttp

for the implementation

Dependency inversion:

UserRepositorer

<-

UserRepositorable