May 2003If Lisp is so great, why don't more people use it?  I was    
asked this question by a student in the audience at a 
talk I gave recently.  Not for the first time, either.In languages, as in so many things, there's not much     
correlation between popularity and quality.  Why does   
John Grisham (King of Torts sales rank, 44) outsell
Jane Austen (Pride and Prejudice sales rank, 6191)?
Would even Grisham claim that it's because he's a better
writer?Here's the first sentence of Pride and Prejudice:

It is a truth universally acknowledged, that a single man 
in possession of a good fortune must be in want of a
wife.

"It is a truth universally acknowledged?"  Long words for
the first sentence of a love story.Like Jane Austen, Lisp looks hard.  Its syntax, or lack
of syntax, makes it look completely unlike 
the languages
most people are used to.  Before I learned Lisp, I was afraid
of it too.  I recently came across a notebook from 1983
in which I'd written:

I suppose I should learn Lisp, but it seems so foreign.

Fortunately, I was 19 at the time and not too resistant to learning
new things.  I was so ignorant that learning
almost anything meant learning new things.People frightened by Lisp make up other reasons for not
using it.  The standard
excuse, back when C was the default language, was that Lisp
was too slow.  Now that Lisp dialects are among
the faster
languages available, that excuse has gone away.
Now the standard excuse is openly circular: that other languages
are more popular.(Beware of such reasoning.  It gets you Windows.)Popularity is always self-perpetuating, but it's especially
so in programming languages. More libraries
get written for popular languages, which makes them still
more popular.  Programs often have to work with existing programs,
and this is easier if they're written in the same language,
so languages spread from program to program like a virus.
And managers prefer popular languages, because they give them 
more leverage over developers, who can more easily be replaced.Indeed, if programming languages were all more or less equivalent,
there would be little justification for using any but the most
popular.  But they aren't all equivalent, not by a long
shot.  And that's why less popular languages, like Jane Austen's 
novels, continue to survive at all.  When everyone else is reading 
the latest John Grisham novel, there will always be a few people 
reading Jane Austen instead.