We love Ruby for being powerful & expressive, but how much power does Ruby have if you remove all of its datatypes except for Proc and all of its features except for Proc.new and Proc#call?
The answer is roughly "the same as before", computationally speaking, but I show this practically by demonstrating proc-only Ruby implementations (i.e. Church encodings) of the booleans, the integers, lists etc and using them to build executable programs. If you haven't seen this before, you may be surprised by how far you can get without any of the "fundamental" operations and datatypes of a conventional programming language.
I'm mostly interested in the parlour game of building these representations and showing how they work; there wasn't time to go into much detail, give much motivation, or assemble much of a broad thread. So this is a fairly practical and hackish exploration of how to build simple datatypes in Ruby using only procs rather than a protracted meditation on the nature of computation.
Given at Ru3y Manor (http://rubymanor.org/3). There's a video of this talk at http://rubymanor.org/3/videos/programming_with_nothing/. The accompanying code is at https://github.com/tomstuart/nothing, and an article version is available at http://codon.com/programming-with-nothing.