I applied Haskell's Applicative Functors to Kotlin Coroutines. Here's what happened.

The author applied Haskell's applicative functor pattern to Kotlin coroutines, building a library called KAP (Kotlin Applicative Parallelism) that distinguishes parallel (applicative) and sequential (monadic) phases in code structure. KAP maps Haskell idioms like lift/ap/flatMap onto Kotlin coroutines, making dependency graphs between concurrent operations explicit without the boilerplate of raw async/await. The post demonstrates how a complex checkout flow with 11 microservice calls across 5 phases becomes more readable and structurally clear using KAP compared to standard coroutine patterns.