TITLE: The Pleasure of Elegant Composition in a Programming Language
AUTHOR: Eugene Wallingford
DATE: January 10, 2013 3:59 PM
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At the 1978 APL Conference, Alan Perlis gave a talk called
Almost Perfect Artifacts Improve only in Small Ways,
in which he said:
What attracted me, then, to APL was a feeling that perhaps
through APL one might begin to acquire some of the dimensions
in programming that we revere in natural language -- some of
the pleasures of composition; of saying things elegantly; of
being brief, poetic, artistic, that makes our natural languages
so precious to us. That aspect of programming was one that
I've long been interested in but have never found any lever
for coming close to in my experience with languages of the
FORTRAN, ALGOL, PL/I school.
I learned APL as as an undergrad and knew immediately that
thinking in it was unlike thinking in any other language I had
learned, even Lisp. These languages, though, shared a Wow!
factor. They enabled programs that did amazing things, or
ordinary things in amazing ways. By contrast, BASIC and
FORTRAN and PL/I seemed so prosaic.
As an undergrad, I never developed the sort of fluency in that
would allow me to, say,
write an assembler in 20 lines of APL
or Lisp. I did develop a fondness for functional programming
that stayed with me into graduate school, where I came into
deeper contact with Lisp. I also learned Smalltalk, which I
came to admire in a way similar to Perlis's feeling for APL.
I must admit, the beauty and expressiveness of array languages
and functional languages have always felt less natural to me
than natural language. Their more mathematical orientation
felt foreign to me, less like writing in a natural language
than solving a puzzle. This wasn't a matter of me not liking
math; I took advanced math throughout school and always enjoyed.
But it felt different to me. This is, I see now, a personal
preference and likely an indicator of why I was drawn more
intimately into computer science than into more study of math.
The language I use these days that makes me feel the way Perlis
feels about APL is Ruby. It occupies a similar space as Python,
which we teach our students and use in several courses. I like
Python a lot, more than I like most languages, but it feels
plain to me in the sense once explained
by John Cook.
It is simple, and I get things done when I program in it, but
when I use it, I feel like I am programming.
Ruby has this goofy, complex syntax that makes it possible to
write some hideous stuff. But Ruby also makes it possible to
write code that is brief and elegant, even artistic.
I first saw this at PLoP many years ago, when looking over
Gerard Meszaros's
shoulder at code he had written to support the writing and
publishing of his XUnit Test Patterns book. His code read like
the book he was writing. Then I began to see DSLs embedded in
Ruby, tools like Rake and Treetop, that made me forget about the
language they were implemented in. When you use those tools and
others like them, you were writing in a new language, one that
fit the thoughts in your head. Yet you were still unmistakably
writing Ruby.
Perhaps if I were more an engineer at heart, I would feel
differently about simple, sturdy languages that let me get things
done. I like them, but they don't make me feel like I am "under
the influence", as Perlis writes. They are just attractive tools.
Perhaps if I were more a mathematician at heart, I would feel
even more at home with the elegance that Haskell and APL give me.
Whatever the reasons, Smalltalk and Ruby grabbed in ways that no
other languages have. I think that is due at least in part to
the way they connected to my personal understanding and love for
natural language. It's interesting how we can all feel this way
about different programming languages. I think it says something
important about the nature of computing and programming.
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