Or, you want to use it in your day-to-day job where it might exist thousands upon thousands of lines of code in a not-so-FP language. I think just learning the

Or, you want to use it in your day-to-day job where it might exist thousands upon thousands of lines of code in a not-so-FP language. I think just learning the concepts is great start. If you could rewrite your whole app, please do so. If not, see if you can write some parts with more FP style code. Like using LINQ in C# instead of rewriting everything to F#, or with Java 8 start using streams and other concepts.