As somebody who has written a lot of Java code before (read imperative) and now have had the opportunity to write more JS (which makes it a bit easier to write

As somebody who has written a lot of Java code before (read imperative) and now have had the opportunity to write more JS (which makes it a bit easier to write Functional) and also Scala, I think the process to "think" functionally takes time. Sure, its easier to apply it to the mathematics domain and harder to something that many of us might think in OO. I guess it comes with taking small steps (as someone already said in a comment). Also, making conscious effort to keep questioning how functional our code is helps. I saw this talk on functionatalks.org by Paul Chiusano (author of Functional programming in Scala) http://functionaltalks.org/2013/06/20/paul-chiusano-how-to-write-a-functional-program-with-io-mutation-and-other-effects/ http://functionaltalks.org/2013/06/20/paul-chiusano-how-to-w... If you see he repeatedly asks how can we make it more functional. I think that is kind of thinking we need to practice. Its hard after too much of imperative thinking I guess. One more thing I have heard is read SICP and forget OO for a bit :).