Can this be fixed with some kind of casting? <https://pl.kotl.in/OTh5QtrfF>

# announcements

[Robert Jaros]

Can this be fixed with some kind of casting?
https://pl.kotl.in/OTh5QtrfF

[Robert Jaros]

other then a as String

[Dominaezzz]

a as Any ?

[streetsofboston]

inline fun <reified T: Any>test1(a: T?): Unit {
    if (a!=null) {
		test2(a)        
    }
}

[Dominaezzz]

Also ☝🏼

[streetsofboston]

This still trips me up that although even when T is bound to Any? , the type-inference can’t cast to to an upper bound to Any after a null-check…. It requires a bit of gymnastics…..

[Dominaezzz]

With the new type inference?

[streetsofboston]

Not sure if it is the new one or the old one… let me find an example….

[streetsofboston]

abstract class State<S, out A> {
    /**
     * Runs this [State]'s computation.
     *
     * It returns a (modified) state of type [S] with a result of this computation of type [A].
     */
    internal abstract val run: (S) -> Pair<S, A>
}

class StateFx<S> {
    private var currentState: S? = null

    fun <B> State<S, B>.bind(): B {
        val (newState, b) = <mailto:[e-mail]|[e-mail]>(currentState)
        currentState = newState

        return b
    }
}

In the above example, <mailto:[e-mail]|[e-mail]>(currentState) shows a compiler error for currentState: Required S, found S?

If I change the currentState as follows,
private var currentState: S = null, then this shows an error: Null cannot be a value of non-null type S
Even though S has upper-bound `Any?`…..

[streetsofboston]

(you can ‘fix’ it by calling <mailto:[e-mail]|[e-mail]>(currentState as S) )

[bbaldino]

i ran into a similar problem when detecting something as an enum and then trying to handle it...because enums require a different upper bound on the type ( <T : Enum<T>>). couldn't find any way to coerce it...I think even a cast there didn't work, but maybe i'm misremembering

[Kroppeb]

https://pl.kotl.in/immbja2td