[Idempotence vs. Referential Transparency] (http://blog.tmorris.net/posts/idempotence-versus-referential-transparency/)
[Kingdom of Nouns] (http://steve-yegge.blogspot.com/2006/03/execution-in-kingdom-of-nouns.html)
[Destroy all ifs] (http://degoes.net/articles/destroy-all-ifs)