

The Roots of Lisp, by Paul Graham

Welcome, parenthesis aficionado, to the first issue of The Clojure Atom!



As we begin our bi-weekly expeditions into Lispy territory, it seems fitting to start with The Roots of Lisp (full article as postscript file), an article by Paul Graham (aka pg of yc, aka The Startup Whisperer) that presents a math-free distillation of the paper which introduced Lisp to the world: John McCarthy's seminal Recursive Functions of Symbolic Expressions and Their Computation by Machine, Part 1.



The Roots of Lisp is a model of technical prose. Concise yet lively and easily understandable, it demonstrates how you can build an expressive model of computation using only a few primitives and a couple syntax rules. Building sophisticated systems from a simple parts is a cornerstone of Lisp programming.



The code samples are fun to read in the same way that proofs are fun to read, with the advantage that they're accessible to those of us who haven't troubled ourselves with the finer points of math notation. (By the way - if that's you, then you'll be pleased with an upcoming issue, where I share with you a great math resource. Math, not maths, because I am an American, and the possibility of more than one math terrifies me.)



I recommend you print the article and read it on a boat or in the woods or, if you're eight or especially whimsical, under the covers with a flashlight. The paper, and the code especially, will reward your full attention. A heads up: If a snippet is challenging, it's useful to read a few paraphs past its introduction because Graham doesn't explain his snippets until after he presents them.



pg has translated McCarthy's paper into Common Lisp; a fun exercise for you would be to translate pg's work into Clojure. Common Lisp will definitely make more appearances in this newsletter; if you're interested in learning it, the best place to start is Land of Lisp.



Thanks for joining me in this adventure, and have fun computing!



Daniel



P.S. I really blew that whole "one link" thing! Please feel free to reply to this email to yell at me about it, or share some resources you'd like to see featured.