But I don't really want to, I want it to cast everything to Any if the user doesn't provide the valu...

# announcements

[LeoColman]

But I don't really want to, I want it to cast everything to Any if the user doesn't provide the value

[Ruckus]

I don't know anything about your use case, but that sounds like a terrible user experience to me in the Kotlin world.

[LeoColman]

It's for a DSL

[LeoColman]

Not exactly to be seen, just to be used

[Casey Brooks]

How does the DSL use that type param? If it matches a function arg, then maybe setting its default value to Any() is what you want?

[LeoColman]

The DSL uses the type param to return a Sequence<T>. Inside the DSL, the values of T may share a common type Y. I want to return Sequence<Y> if they do, and Sequence<Any> if they don't

[LeoColman]

It's for something like:

class Y
class A : Y
class B : Y

buildSequence<Y> {
      creatingValue<A> { A() }
      creatingValue<B> { B() }
}

[LeoColman]

The compiler can't infer the type this way, and I didn't want the user to be forced to write buildSequence<Y>, just buildSequence { } which would return Sequence<Y>

[LeoColman]

And perhaps for the user Sequence<Any> is enough

[Casey Brooks]

Messing around type projections or bounds might be what you’re after, though I’m not familiar enough with them to know if they will fit this use-case https://kotlinlang.org/docs/reference/generics.html#variance

[LeoColman]

I tried to mess with many of them 😕

[LeoColman]

Perhaps I"m overthinking this, and there's no problem in typing buildSequence<Any> if the user wants it

[streetsofboston]

Try to use this annotation. It may help.
@BuilderInference

[streetsofboston]

E.g. there is this code building a `Flow<T>`:

public fun <T> flow(@BuilderInference block: suspend FlowCollector<T>.() -> Unit): Flow<T> = SafeFlow(block)

Just by calling emit(instancOfMyType) in the provided lambda (argument to block), the compiler can infer that T is MyType

[LeoColman]

That seems interesting!

[LeoColman]

Let me try

[streetsofboston]

https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-builder-inference/index.html

[LeoColman]

And the example is practically my use case

[LeoColman]

How can I use the @Experimental without requiring the compiler flag for the client to use?

[streetsofboston]

I think you’d have to mark this part of your API as experimental as well, since it promises something to the user of your API that only this experimental feature can offer.

[LeoColman]

Unfortunately it didn't work. still getting the "Not enough information to infer parameter"

[LeoColman]

Any tips, @streetsofboston?

[LeoColman]

It works if I enable the new type inference

[LeoColman]

I think that's the point, right? xD