From Haxl paper:<p>&quot;We present an Applicative abstraction that allows implicit concurrency to be extracted from computations written with a combination of Monad and Applicative.&quot;<p>The more your code is Applicative the more concurrency you can extract. It&#x27;s a matter of good abstractions rather than the language. I&#x27;m sure Rust can handle Applicative and Monad just fine.