Richard Warburton - Java 8 Lambdas: Pragmatic Functional Programming

For years, functional programming has been considered the realm of a smallband of specialists who consistently claimed superiority to the masseswhile being unable to spread the wisdom of their approach. The mainreason Ive written this book is to challenge both the idea thattheres an innate superiority in the functional style and the belief that its approachshould be relegated to a small band of specialists!

For the last two years in the London Java Community, Ive been gettingdevelopers to try out Java 8 in some form or another. Ive found that many of ourmembers enjoy the new idioms and libraries that it makes available to them. Theymay reel at the terminology and elitism, but they love the benefits that a bitof simple functional programming provides to them. A common thread is howmuch easier it is to read code using the new Streams API to manipulate objectsand collections, such as filtering out albums that were made in the UK from aList of all albums.

What Ive learned when running these kinds of events is that examples matter.People learn by repeatedly digesting simple examples and developing anunderstanding of patterns out of them. Ive also noticed that terminology canbe very off-putting, so anytime theres a hard-sounding concept, I give aneasy-to-read explanation.

For many people, what Java 8 offers by way of functional programmingis incredibly limited: no monads,[] no language-level lazy evaluation, no additional support forimmutability. As pragmatic programmers, this is fine; what we want is theability to write library-level abstractions so we can write simple, clean codethat solves business problems. Were even happier if someone else has writtenthese libraries for us and we can just focus on doing our daily jobs.