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

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?