Ruby Conf 12: "Boundaries" - Gary Bernhardt
https://www.youtube.com/watch?v=yTkzNHF6rMs
"Boundaries" - Gary Bernhardt from SCNA 2012
https://www.destroyallsoftware.com/talks/boundaries
Business-Friendly Functional Programming, Part 2: Testability - Yang Bo
http://rea.tech/business-friendly-functional-programming-part-2-testability/
Functional Programming in Swift - slide 55+
http://www.slideshare.net/SaugatGautam2/functional-programming-in-swift
Enemy of the State by Justin Spahr-Summers
https://speakerdeck.com/jspahrsummers/enemy-of-the-state
"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
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
Functional Programming in Ruby - Vitor Capela
https://speakerdeck.com/dodecaphonic/functional-programming-in-ruby
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
BoochTek, LLC
http://blog.boochtek.com/category/programming/architecture
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/