What does it mean to declare main as

suspend

, ie.

suspend fun main() { ... }

? Is it equivalent to having

fun main() = runBlocking { ... }

or something else?

Not exactly, runBlocking also creates CoroutinesScope, so you can use launch/async/etc coroutines builders

Right, didn’t think about coroutine builders. My main was just calling other suspend functions

runBlocking

also confined your coroutines to the main thread (install its own distacher), but the code in

suspend main

executes in a default dispatcher. Only really matters when yo go

coroutineScope { ... }

and start launching coroutines from there.

Is there a reason for this difference?

@simon.vergauwen Yes.

runBlocking

is not the default dispatcher at all, but uses the (single) thread it blocks as the dispatcher. Very different from using

suspend fun main()

and letting it use the default dispatcher (quite correctly named

Dispatchers.Default

).

Thanks. Why doesn't

suspend fun main()

start on main?

For simplicity. It is built into the language, as opposed high-level library function like

runBlocking