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Ruby provides the programmer with a set of very powerful features borrowed from the domain of functional programming, namely closures, high-order functions and first-class functions [1]. These features are implemented in Ruby by means of code blocks, Proc objects and methods (that are also objects) - concepts that are closely related and yet differ in subtle ways. In fact I found myself quite confused about this topic, having a difficulty to understand the difference between blocks, procs and methods and unsure about the best practices of using them. Additionally, having some background in Lisp and years of Perl experience, I was unsure of how the Ruby concepts map to similar idioms from other programming languages, like Lisp’s functions and Perl’s subroutines. Sifting through hundreds of newsgroup posts, I saw that I’m not the only one with this problem, and in fact quite a lot of “Ruby Nubies” struggle with the same ideas.