The How and Why of Fitting Things Together - Joe Armstrong 

The key part is at 33:56 that states that Types + FSM specifies the contract between communicating entities as the means to "Fit Things Together".

Mills and Dijkstra were adamant about proving correctness before writing a line of code.

24:05

I feel like a lot of people could chill right out if they knew joe had solved all their problems for them in the 80s

It is - most probably intrinsically - impossible to design and implement things that will fit together. The best we can aim/hope for are things that can be glued together 'as they are' where the glue has to provide and deliver significant functionality (and perform some syntax-level conversions). Inherently, 'design for the unexpected' only delivers intermediate and partial solutions where the 'finishing of the task at hand' will involve commitments that cannot survive future requirements. More info: store.elsevier.com/Design-for-the-Unexpected/Paul-Valckenaers/isbn-9780128036624/

Erlang as a universal middle layer language Theory: Order decreases to O(N) Practice: Order increases to O( (N+1)²) ....

That is a gross misrepresentation of the purpose of HTTP. It's almost never used for transferring static files anymore.