jaredshay/fubby

Functional ruby library

Fubby

Fubby is a collection of functional concepts written from first principles in ruby.

The library can be used as a gem however it is not advised for production use.

This project is academic and prioritizes a very particular coding style over performance and readability. As an example here is a function that performs the same role as ruby's all?

  def f_all
    C.curry.(
      ->(f, xs) {
        !any.(->(x) { x == false }, map.(f, xs))
      }
    )
  end

There are a lot of inefficiencies here. For starters every function call in this library uses the lambda syntax: ->(...) { }. This leads to a "double" declaration of every function as the def <method_name> is only used as a wrapper to help organize code. Ignoring the def f_all and the C.curry lines we are left with:

  ->(f, xs) {
    !any.(->(x) { x == false }, map.(f, xs))
  }

Unwrapping this further we find both any and map are implemented in terms of a implementation of reduce. Writing all the code out would be confusing to read so I'll stop here, you can read the code further if you want to understand it. This should highlight why this code is not a good candidate for anything other than furthering your understanding of ruby and functional concepts. The main reasons are:

1. It is not performant. An optimized all implementation would be able to short circuit when a value does not satisfy the checking function.
2. All the iteration is recursive and there are many passes over the same collection to arrive at the result.
3. There are a ton of closures. For something as straightforward as all there is a lot of space overhead required to keep all the calling contexts in scope.
4. There is no type checker. For most of the code to work in this library you need to manually ensure the contracts between functions are correct. Ruby isn't going to help here so there is a lot of mental gymnastics required to figure out if you are calling everything correctly. Honestly even if ruby could help I'd be impressed if you still didn't have a hard time. I struggle to get my head back into how this is all written whenever I re-visit it...

What should I do with this code?

Read it! Then think about how you would write the same thing. Or even better, go ahead and try and write some of this yourself. I've tried to stick to conventions for naming and comments so searching for particular terms or function names will yield a lot more reading on anything I've written here.

License

MIT