RubyConf 2008: Better Ruby through Functional Programming

Posted in Conferences, Development on December 03, 2008

RubyConf 2008: Better Ruby through Functional Programming

Functional Programming (FP) has become interesting lately as the most robust way to write highly-concurrent applications. However, applying functional ideas can benefit your applications in other ways, too. This talk will describe the key ideas in functional programming, the functional-like features that Ruby already supports, and how you can improve your code by leveraging functional programming ideas.

Ruby supports several functional programming features. You can make variables immutable (value objects) and you can write functions with no side effects, meaning they don't modify any global or object state and all the work they do is returned by the functions. These characteristics may sound restrictive, but they eliminate common bugs, as we will see.

These characteristics also make concurrency easier, as there is no state shared between threads that requires synchronization! We will examine functional-style concurrency in Ruby, using the Actor model, for example.

Functions are "first class citizens" in functional programming (as the name might imply), meaning you can assign them to variables and pass them as arguments to other functions. Of course, Ruby already supports functions (methods) as first-class citizens and closures are anonymous functions.

Ruby DSL's are naturally declarative in nature, like most functional code. Code simplification is a major benefit in large, non-trivial applications!

Along the way, we will see a few other useful functional techniques, like ways to avoid using nil values and better use of arrays, maps, and pattern matching.

When finished, you will have a new appreciation for the benefits that functional programming can bring to your Ruby projects.

About Dean Wampler
I'm a consultant at Object Mentor, "Uncle Bob's" company. Recently, I've focused on "polyglot and poly-paradigm programming"; how to combine languages and modularity "paradigms" (OOP, FP, aspect-oriented programming, etc.) to implement applications in the most effective way. In particular, I have started using Functional Programming ideas to improve my Ruby code.

My open source projects are Aquarium (, an aspect-oriented toolkit for Ruby, Contract4J (, a design-by-contract tool for Java, and I've contributed to FitNesse (, an acceptance testing tool for many languages.

I blog frequently on the Object Mentor blog,

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Tags: Conferences, Ruby, DSL, Functional Programming, Confreaks, RubyConf 2008