I keep trying to do

return <whatever>

from lambdas - I know I just need to remove the

return

, but can anyone explain the error message to me? From the expected type it looks as if the

return

from within the lambda is capable of terminating the enclosing function call - how is this possible? Would this pop the stack from the lambda, the

partition

call, and the enclosing function - like a

throw

?

It is only possible in inline functions

Ahh I see - so the lambda, and the partition function get inlined directly into the enclosing function. Got it - so is there a way to know when this will happen? Or will it just be that in some cases I could short-cut return straight from the middle of an operation, and sometimes not?

The majority of lambda-accepting methods are inline for performance reasons

oh great.. and the

filter

too then (I missed that one)

yeah, most of the functional collections extensions are inlined

This is from the Kotlin Koans, and it asks you to implement it using

partition

. However I initially didn’t see this and implemented it using what I’d learned so far. However looking at the code again, will the

partition

in my example create two collections vs the commented out implementation which doesn’t create any collections and just iterates the existing one once (in the

count{}

)?

hmmm there looks like two calls to

.count()

though

Yeah but the second is just

count()

- no predicate, so it just returns

size

in any case, the extra collections are more or less just views on the original collection, I’m pretty sure

CMD-clicking

partition

takes me to the implementation which creates two array lists.

perhaps ¯\_(ツ)_/¯