How best to call suspend functions from `Sequence.map` and `flatMap`? These operations on `Sequence`...

# coroutines

[rocketraman]

How best to call suspend functions from Sequence.map and flatMap? These operations on Sequence are not inlined, unlike List, so you get the error Suspension functions can only be called within coroutine body. I don't want to use runBlocking inside the lambda.

[Jonathan]

Use channel instead of sequence.

[Jonathan]

Of course it has its limitation, and you may want to read: https://github.com/Kotlin/kotlinx.coroutines/issues/254

[rocketraman]

Thanks @Jonathan!

[Dico]

Maybe contracts can be used to capture the continuation from within lambdas.

[Jonathan]

@Dico. No lambda is not executed in place. The problem is that we don't know on which context the lambda of Sequence.map will be executed (or if it will be executed at all). This is inherent to sequences since everything will be evaluated lazily on the context of iterator's usage.

[Dico]

Right, the static extension functions of Sequence can't make any guarantees about where/when the programmer invokes a terminal operation.