How do I express in a contract that a condition is...

# stdlib

[Youssef Shoaib [MOD]]

How do I express in a contract that a condition is true inside a lambda? As in, I want to combine the power of returns with callsInPlace. For instance, I have an inline higher-order function that takes an enabled: Boolean parameter, and it only calls the block passed to it if enabled is true. How do I say that enabled is true inside of the block?
E.g.:

@OptIn(ExperimentalContracts::class)
inline fun runIf(condition: Boolean, block: () -> Unit) {
    contract { 
        callsInPlace(block, InvocationKind.AT_MOST_ONCE)
    }
    if(condition) block()
}

fun main() {
    val test: String? = "Hello"
    runIf(test != null) {
        test.length
    }
}

Yes that example is stupid, but my use-case provides parameters to block and hence it can't just return a Boolean

[dmitriy.novozhilov]

https://youtrack.jetbrains.com/issue/KT-32993

[dmitriy.novozhilov]

We plan to implement this feature after release of 2.0

[simon.vergauwen]

Not sure if it’s related but I’m Arrow we also define contracts in some places and it doesn’t work outside of the Arrow compilation unit.

So downstream projects cannot benefit from it, https://github.com/arrow-kt/arrow/blob/b1ad7f713a68c24c8ae0105cbc4d2c9409e575ff/arrow-libs/core/arrow-core/src/commonMain/kotlin/arrow/core/Either.kt#L518

After checking if(either.isRight()) I would expect to be able to access the value property of Either.Right. Is this related?