rns, which stands for "Ruby namespaces", is a small library for using classes and modules as packages of functions in order to support functional programming in Ruby. It is inspired by Clojure's ns macro and namespace system.

require 'rns'

Arithmetic = Rns do
  def dec(n) n - 1 end
  def inc(n) n + 1 end
end

Statistics = Rns do
  def avg(arr) arr.reduce(:+).to_f / arr.count end
end

class Main
  Funcs = Rns(Statistics, Arithmetic => [:inc]) do
    def incremented_avg(nums)
      avg nums.map(&method(:inc))
    end
  end

  def main
    nums = [1, 2, 3]
    puts "The average of #{nums.inspect} incremented is: #{Funcs.incremented_avg nums}"
  end
end

Main.new.main

Please see the tests for more usage examples.

Ruby has good functional programming support, but the class and module system doesn't lend itself to organizing and accessing functions. With rns I hope to make it at least slightly easier to build Ruby programs primarily out of pure functions.

To Sam Umbach for helping me tame the eigenclass, and to my employer Relevance for indulging me with time to work on free software.