programming, when stripped of all its circumstantial irrelevancies,
boils down to no more and no less than very effective thinking so as to avoid unmastered complexity,
to very vigorous separation of your many different concerns.
-- Dijkstra EDW512
https://www.cs.utexas.edu/users/EWD/transcriptions/EWD05xx/EWD512.html
"Boundaries" - Gary Bernhardt
https://www.youtube.com/watch?v=yTkzNHF6rMs
https://www.destroyallsoftware.com/talks/boundaries
there are only two roles of code - John Sonmez
https://simpleprogrammer.com/2012/10/21/there-are-only-two-roles-of-code/
Object layer, valuelayer (27:53-) - Andy Matuschak
https://realm.io/news/andy-matuschak-controlling-complexity/
"Functional core & Imperative shell" : OO design, and isolated tests without mocks
http://blogs.perl.org/users/mascip/2014/06/functional-core-imperative-shell-oo-design-and-isolated-tests-without-mocks.html
http://blogs.perl.org/users/mascip/2014/06/functional-core-imperative-shell-explanation-with-code.html
Business-Friendly Functional Programming, Part 2: Testability - Yang Bo
http://rea.tech/business-friendly-functional-programming-part-2-testability/
mokacoding - unit and acceptance testing, automation, productivity
http://www.mokacoding.com/blog/functional-core-reactive-shell/
Functional Core, Imperative Shell - Sean Hammond
http://www.seanh.cc/posts/functional-core-imperative-shell
BoochTek, LLC
http://blog.boochtek.com/category/programming/architecture
Functional Programming in Ruby - Vitor Capela
https://speakerdeck.com/dodecaphonic/functional-programming-in-ruby
Enemy of the State by Justin Spahr-Summers
https://speakerdeck.com/jspahrsummers/enemy-of-the-state
Functional Programming in Swift - slide 55+
http://www.slideshare.net/SaugatGautam2/functional-programming-in-swift
Test-Driven Development with Python - Harry Percival
https://books.google.dk/books?id=fTLJAwAAQBAJ&pg=PA403&lpg=PA403&dq=%22functional+core%22+%22imperative+shell%22&source=bl&ots=A4g25w7wWY&sig=x0bu4NZWiXrpzWPziAH7Y78AKgM&hl=en&sa=X&ved=0ahUKEwi0jq3em-zPAhUqG5oKHYNJBIE4ChDoAQhRMAk#v=onepage&q=%22functional%20core%22%20%22imperative%20shell%22&f=false
https://www.destroyallsoftware.com/blog/2014/test-isolation-is-about-avoiding-mocks
To Kill a Mockingtest - Ken Scambler
http://rea.tech/to-kill-a-mockingtest/