Common Lisp

Hey! Thanks for reading! Just a reminder that I wrote this some years ago, and may have much more complicated feelings about this topic than I did when I wrote it. Happy to elaborate, feel free to reach out to me! 😄

I've been playing around with Common Lisp recently, using Practical Common Lisp and Let Over Lambda as guides (not gonna lie, having LOL on the spine of your book is wonderful). Last year when I went through my Scheme phase (the original URL of this blog was littleschemer.blogspot.com), I never thought I'd see the day that I'd switch sides.

FWIW, this is my iPhone background image.

I do feel like a traitor though, since even though I'm a theory-head and advocate of FP, I'm loving Common Lisp. There are a few reasons for this:

• Simpler macros. I'll bet some hardcore Schemers will disagree with me on this, but I feel that defmacro is much, much simpler to learn than syntax-case, and syntax-rules always leaves me wanting more. Maybe I'm deficient, but I took to defmacro immediately, whereas when I want to do anything non-trivial in Scheme, I feel myself always going back to Dybvig's explanations, taking far longer than I'd like.
  
  While in principle I'm for hygiene as the default, it's not too big an issue in practice. Hoyte gives a great little macro (one of the first in his book) that ensures you fresh variables whenever you want them, without even having to declare them!

• Language libraries. CL comes with every function you could ever want. It comes back to what Peter Norvig said in Paradigms in Artificial Intelligence Programming (paraphrasing): Scheme is one of the smallest languages to define (< 50 pages), whereas CL is one of the largest (> 1200 pages).
  
  While some Schemes provide these, since they aren't part of the standard you aren't guaranteed anything across implementations. In fact, my favorite Scheme in terms of libraries (good ole' PLT) even broke across versions when they enforced module declarations at the top of every file.
  
  Besides, once a Scheme gets these, they stop wanting to be called Scheme.

This isn't to say its all peaches and cream: I still prefer Scheme's single namespace over Common Lisp's, I prefer Scheme's naming conventions (map vs. mapcar, or worse, loop for elem in list collecting). And issues with lambdas, namely sharp-quoting and not being able to place functions in the function position (especially after learning the beauty of Scheme's semantics so well last semester) still throw me for a loop.

But after a year of mounting tension with the residents of Shelbyville, I realize they've got quite a bit right ^_^.