While not a mainstream practice in the PHP world, functional programming has been a topic that's popped up again and again over the years. If you've ever wondered what it's all about and how to get started with it in your applications, take a look at php[architect].
This book is for anyone that has an interest in functional programming or PHP as an advanced programming language. If you are curious or have never even heard of functional programming before then this is the gentle introductory text you have been looking for. Equally it serves those seeking to exploit the advanced functional concepts such as monads in a PHP context.
This book comes from some of the experience Simon has had with functional programming in the past (and taught about in presentations). It provides examples showing the techniques of functional programming applied in PHP including: map/reduce, currying and composition. The book can be purchased either directly from php[architect] or from Amazon (or Amazon.co.uk).