Firstly, we delve into writing a library for doing parallel computation in a purely functional way. This gives us a chance not only to examine parallelism, but to also to examine how to write modular functional libraries by separating the description of a computation (via algebras) vs actually running them.

Secondly, we will write a property based testing library through which we can write high level specifications of the laws that we expect to hold for our program and have other machinery generate test data and provide counterexamples if our properties fail. Through this journey, we will start seeing the similarities between this API design and our parallel execution library, which will allow us to start teasing out the essence of writing purely functional libraries.