Functional paradigm design [closed]

Question

I have been asked to capture the design of the system that is implemented by applying functional programming principles in C#. Requirements for this are to use any kind of formalism to describe the design, rather than informal English. Also, usage of UML is forbidden.

I have chosen to try using F# for these purposes, but am having difficulties to keep abstraction level high without going into re-implementation of everything using F#.

So I have few questions:

1. Is there any architectural framework/practice how to describe functional design?

2. How can I expose methods without implementation details?

3. How to create component interfaces in F#?

4. In OO you usually have different views for architecture (like 4+1, for example). Is there something like that for functional design?

Answer 1

TLDR it's all about composition.

Everything where you are required to use HKT (think of them as Generic Generics) is mostly a huge asset for library design, when you're going for pure functional programming it's fundamentally different than the GO4 mindset, or the new buzzword of the week for enterprise programming.

Learn Haskell, learn about Monads, Functors, Applicatives, Monoids, etc.(Don't be scared you've used them over 9000 times by now without realizing it) Then look into stuff like the Free Monad, scrap your boiler plate, lenses, Typeclasses, and MTL style transformers and afterwards you'll be a much better library programmer.