If you maintain code that is a gigantic ball of if-foreach-else-switch-is_null or your class hierarchy looks like something a Java developer would produce, and

If you maintain code that is a gigantic ball of if-foreach-else-switch-is_null or your class hierarchy looks like something a Java developer would produce, and you are constantly thinking "there must be a better way," you might benefit from exploring Haskell or a language with some of its features. PHP is actually one of those languages, since it gained real support for first-class functions, anonymous functions and closures starting with 5.3 and improving with 5.4. So if you do learn Haskell you'll be able to directly apply some of its ideas to making your PHP more concise, easier to test, and less error prone. Check out the PHP Underscore library to provide some of the infrastructure: http://brianhaveri.github.io/Underscore.php/ http://brianhaveri.github.io/Underscore.php/ Haskell brings a lot more to the table than first class functions, and it may or may not be a good introduction to functional programming for you, but other functional(-ish) languages such as Scala or Clojure (or Scheme & other Lisps) will work well, too. Just give it time. It's worth the effort, but you're not going to magically transform your code into the Unicorn Monad overnight. If you do PHP you probably do a lot of JavaScript, too, so there is another language that supports getting into functional programming, and there is definitely a lot of interest in moving JavaScript in more classically functional direction. So you won't be blindsided by maps, folds and promises. I apologize if you already use first class functions like a boss and you were really asking if you needed static type inference. The answer is Maybe.