Why does the following code compile? ```fun <T,...

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[Orhan Tozan]

Why does the following code compile?

fun <T, R> Result<T>.letIfSuccess(
    block: (data: T) -> Result<R>
): Result<R> = when (this) {
    is Result.Failure -> this
    is Result.Success -> block(this.data)
}

letIfSuccess returns Result<R> , but returns Result<T> when first branch of when statement is met.

I would expect it to give it a compile error, as Result<T> !is Result<R> .

[Ruckus]

Result.Failure is Result<Nothing>, whick is always satisfied.

[Orhan Tozan]

Indeed, figured it out. Works great, almost magic.