Frameworks are not yet well refactored libraries.

At first we had Catalyst. After some refactoring we got HTTP::Engine and now we have PSGI/Plack and the tools around that abstraction that provide a lot of functionality that previously required using Catalyst. Now all of that is in libraries that can be used independently from each other, there is no coupling between the components other than the well defined and pretty minimal PSGI interface.

The title of this blog post might not be universally true, it is possible that there are some kernel parts in some frameworks or even most of the frameworks that could never be in any practical way reduced into sets of libraries. But what I observe is that frameworks tend to grow and only in very exceptional cases spawn libraries that are refactored out of their main body. It is just so much easier to just write new extensions, plugins or things that use the whole framework than find the right abstraction that would let to split some functionality out of the main code base. Certainly I would never guess that the simple PSGI abstraction would let people refactor so much into separate libraries, I bow to it's author. But we should always try:

Perfection is achieved, not when there is nothing more to add, but when there is nothing left to take away.

Antoine de Saint-Exupery