I believe at the moment the Kotlin compiler is mis...

# language-proposals

[raulraja]

I believe at the moment the Kotlin compiler is missing a single feature to guarantee pure functions to those that care.
The Kotlin compiler already is able to track effects with suspend and @RestrictsSuspension which enables users to encode functions that produce effects with suspend. This is awesome and is what we've built Arrow Fx upon.
What the Kotlin compiler is currently missing or maybe I failed to find a way is for users to disallow in their code bases function application when functions return Unit and they are not inside suspend.
With such a feature which could be activated via import, scoped annotations or simple compiler flag the Kotlin compiler would be able to a la carte guarantee function purity which is something not even scalac or other inclined FP langs in the JVM provide.
This would be opt-in and would not affect anyone that does not care about this feature. What are your thoughts on this potential feature. If there is interest I will submit a KEEP after @tomasruizlopez and @Jorge Castillo submit KEEP-87 this week.