Lisping at JPL Revisited

It has been over 20 years since I wrote "Lisping at JPL", half memoir and half geeky screed (and all of it half-baked) about how an obscure programming language came to define my career.  It was a borderline throwaway piece written as much to vent my spleen as to inform.  In the intervening two decades it has gotten a lot more attention than I ever expected, becoming a perennial favorite on Hacker News, launching my (very short) career as a podcast guest, and even inspiring some people to plagiarize it, which make me feel simultaneously flattered and annoyed.

User marai2 over on HN made this suggestion the last time L@J was posted on HN:

Since this essay cycles here on HN perennially and inevitably people are curious about how your views about lisp, or other languages have changed, you might want to have a follow up page that you forever keep on updating as your views change?

So, by request...

My views on Lisp have not changed: Common Lisp is still far and away my favorite programming language, but that is mainly because I don't really program in Common Lisp any more. I program in a little custom language that I have incrementally built on top of Common Lisp over the years. This language consists mainly of a single macro called BINDING-BLOCK which is a stand-alone replacement for almost all of the other binding constructs in Common Lisp and makes my code look very different from most CL code. In particular, my code has a lot fewer parentheses, and it doesn't run off the right side of the screen as much.  (Here is an example.)  A CL programmer looking at my code would probably go, "WAT?" And when I look at regular CL code nowadays I go "blech!" Especially if that code uses LOOP. Then I go double-blech, despite the ironic fact that LOOP and BINDING-BLOCK have a lot in common.

All this is a reflection of the so-called Lisp curse, the fundamental problem with Lisp -- its great strength is simultaneously its great weakness.  It is super-simple to customize Lisp to suit your personal tastes, and so everyone does, and so you end up with a fragmented ecosystem of little sub-languages, not all of which (to put it mildly) are particularly well designed.

But *I* am 10x more productive in CL than in any other language. And not just CL, but one particular CL environment, Clozure Common Lisp, which I have been using since it was Coral Common Lisp running on a Macintosh Plus with one 800k floppy disk and one megabyte of RAM. CCL is probably the most under-appreciated engineering marvel ever produced by any species other than termites. I have been using it for 38 years. (Unfortunately, that era is likely drawing to a close.  Clozure Associates is no longer a going concern, and the volunteer effort to port CCL to the M1 appears to have stalled. This makes me very sad. It is truly the end of an era, and a very long one by technological standards.)

People often ask me what I think about other languages, and Clojure in particular. My answer is that I have never used Clojure, but from what I have read it looks pretty neat. But I think no other language can ever possibly be better than Common Lisp for me because I have customized the hell out of my environment until it is exactly the way I want it. It is quite literally the perfect language for me because I have made it that way -- because I was able to make it that way. Any time I find something about it I don't like, I can change it quickly and easily. Nothing that someone else designs can ever compete with that. Even I can't compete with that. Every now and then I toy with the idea of building my own Lisp from scratch, and I once took a semi-serious whack at it as an exercise to try to learn C++, but I gave up when it became clear that the effort required to make it competitive with CCL plus 38 years of incremental tweaking was vastly more than I was willing to invest.

There is one feature of Common Lisp that I absolutely love which no other language offers AFAIK, and that is a generic-function model of objects.   IMHO, the goal of a programming language ought to be to make writing code as easy and free of cognitive load as possible.  If I want to do an operation, I want to be able to say (op arg1 arg2 ... argn) without having to think about whether OP is a plain function or a method or an operator.  In every other language I have to think about whether to write op(arg1, arg2 ... argn) or arg1.op(arg2, ... argn) or "arg1 op arg2" or, in Objective C, [arg1 op:arg2 someRandomThing:arg3 ... someOtherRandomThing:argn].  In Lisp I never have think about that.  I just write (op arg1 .. argn) and it does the right thing.

So the bottom line is: I still love Common Lisp.  YMMV.

My second favorite language at this point is Python.  It has a lot of nifty features, and a clean design that is mostly free of gotchas.   Ironically, I don't like Python's most iconic feature, the syntactically significant white space.  Python claims to not use braces, but this is half a lie.  It does use an open brace, it just uses the colon character to serve that purpose.  So in my code I use the "pass" statement as a de-facto close-brace, so when I use emacs python-mode, my code always auto-indents correctly.

But the best programming language is like the best wine.  Different people like different things, and that's OK.  Drink whatever is the best fit for your palate, and code in whatever is the best fit for your brain.