January 2003(This article is derived from a keynote talk at the fall 2002 meeting
of NEPLS.)Visitors to this country are often surprised to find that
Americans like to begin a conversation by asking "what do you do?"
I've never liked this question.  I've rarely had a
neat answer to it.  But I think I have finally solved the problem.
Now, when someone asks me what I do, I look them straight
in the eye and say "I'm designing a 
new dialect of Lisp."   
I recommend this answer to anyone who doesn't like being asked what
they do.  The conversation will turn immediately to other topics.I don't consider myself to be doing research on programming languages.
I'm just designing one, in the same way that someone might design
a building or a chair or a new typeface.
I'm not trying to discover anything new.  I just want
to make a language that will be good to program in.  In some ways,
this assumption makes life a lot easier.The difference between design and research seems to be a question
of new versus good.  Design doesn't have to be new, but it has to  
be good.  Research doesn't have to be good, but it has to be new.
I think these two paths converge at the top: the best design
surpasses its predecessors by using new ideas, and the best research
solves problems that are not only new, but actually worth solving.
So ultimately we're aiming for the same destination, just approaching
it from different directions.What I'm going to talk about today is what your target looks like
from the back.  What do you do differently when you treat
programming languages as a design problem instead of a research topic?The biggest difference is that you focus more on the user.
Design begins by asking, who is this
for and what do they need from it?  A good architect,
for example, does not begin by creating a design that he then
imposes on the users, but by studying the intended users and figuring
out what they need.Notice I said "what they need," not "what they want."  I don't mean
to give the impression that working as a designer means working as 
a sort of short-order cook, making whatever the client tells you
to.  This varies from field to field in the arts, but
I don't think there is any field in which the best work is done by
the people who just make exactly what the customers tell them to.The customer is always right in
the sense that the measure of good design is how well it works
for the user.  If you make a novel that bores everyone, or a chair
that's horribly uncomfortable to sit in, then you've done a bad
job, period.  It's no defense to say that the novel or the chair  
is designed according to the most advanced theoretical principles.And yet, making what works for the user doesn't mean simply making
what the user tells you to.  Users don't know what all the choices
are, and are often mistaken about what they really want.The answer to the paradox, I think, is that you have to design
for the user, but you have to design what the user needs, not simply  
what he says he wants.
It's much like being a doctor.  You can't just treat a patient's
symptoms.  When a patient tells you his symptoms, you have to figure
out what's actually wrong with him, and treat that.This focus on the user is a kind of axiom from which most of the
practice of good design can be derived, and around which most design
issues center.If good design must do what the user needs, who is the user?  When
I say that design must be for users, I don't mean to imply that good 
design aims at some kind of  
lowest common denominator.  You can pick any group of users you
want.  If you're designing a tool, for example, you can design it
for anyone from beginners to experts, and what's good design
for one group might be bad for another.  The point
is, you have to pick some group of users.  I don't think you can
even talk about good or bad design except with
reference to some intended user.You're most likely to get good design if the intended users include
the designer himself.  When you design something
for a group that doesn't include you, it tends to be for people
you consider to be less sophisticated than you, not more sophisticated.That's a problem, because looking down on the user, however benevolently,
seems inevitably to corrupt the designer.
I suspect that very few housing
projects in the US were designed by architects who expected to live
in them.   You can see the same thing
in programming languages.  C, Lisp, and Smalltalk were created for
their own designers to use.  Cobol, Ada, and Java, were created   
for other people to use.If you think you're designing something for idiots, the odds are
that you're not designing something good, even for idiots.
Even if you're designing something for the most sophisticated
users, though, you're still designing for humans.  It's different 
in research.  In math you
don't choose abstractions because they're
easy for humans to understand; you choose whichever make the
proof shorter.  I think this is true for the sciences generally.
Scientific ideas are not meant to be ergonomic.Over in the arts, things are very different.  Design is
all about people.  The human body is a strange
thing, but when you're designing a chair,
that's what you're designing for, and there's no way around it.
All the arts have to pander to the interests and limitations
of humans.   In painting, for example, all other things being
equal a painting with people in it will be more interesting than
one without.  It is not merely an accident of history that
the great paintings of the Renaissance are all full of people.
If they hadn't been, painting as a medium wouldn't have the prestige
that it does.Like it or not, programming languages are also for people,
and I suspect the human brain is just as lumpy and idiosyncratic
as the human body.  Some ideas are easy for people to grasp
and some aren't.  For example, we seem to have a very limited
capacity for dealing with detail.  It's this fact that makes
programing languages a good idea in the first place; if we
could handle the detail, we could just program in machine
language.Remember, too, that languages are not
primarily a form for finished programs, but something that
programs have to be developed in.  Anyone in the arts could
tell you that you might want different mediums for the
two situations.  Marble, for example, is a nice, durable
medium for finished ideas, but a hopelessly inflexible one
for developing new ideas.A program, like a proof,
is a pruned version of a tree that in the past has had
false starts branching off all over it.  So the test of
a language is not simply how clean the finished program looks
in it, but how clean the path to the finished program was.
A design choice that gives you elegant finished programs
may not give you an elegant design process.  For example, 
I've written a few macro-defining macros full of nested
backquotes that look now like little gems, but writing them
took hours of the ugliest trial and error, and frankly, I'm still
not entirely sure they're correct.We often act as if the test of a language were how good
finished programs look in it.
It seems so convincing when you see the same program
written in two languages, and one version is much shorter.
When you approach the problem from the direction of the
arts, you're less likely to depend on this sort of
test.  You don't want to end up with a programming
language like marble.For example, it is a huge win in developing software to
have an interactive toplevel, what in Lisp is called a
read-eval-print loop.  And when you have one this has
real effects on the design of the language.  It would not
work well for a language where you have to declare
variables before using them, for example.  When you're
just typing expressions into the toplevel, you want to be 
able to set x to some value and then start doing things
to x.  You don't want to have to declare the type of x
first.  You may dispute either of the premises, but if
a language has to have a toplevel to be convenient, and
mandatory type declarations are incompatible with a
toplevel, then no language that makes type declarations  
mandatory could be convenient to program in.In practice, to get good design you have to get close, and stay
close, to your users.  You have to calibrate your ideas on actual
users constantly, especially in the beginning.  One of the reasons
Jane Austen's novels are so good is that she read them out loud to
her family.  That's why she never sinks into self-indulgently arty
descriptions of landscapes,
or pretentious philosophizing.  (The philosophy's there, but it's
woven into the story instead of being pasted onto it like a label.)
If you open an average "literary" novel and imagine reading it out loud
to your friends as something you'd written, you'll feel all too
keenly what an imposition that kind of thing is upon the reader.In the software world, this idea is known as Worse is Better.
Actually, there are several ideas mixed together in the concept of
Worse is Better, which is why people are still arguing about
whether worse
is actually better or not.  But one of the main ideas in that
mix is that if you're building something new, you should get a
prototype in front of users as soon as possible.The alternative approach might be called the Hail Mary strategy.
Instead of getting a prototype out quickly and gradually refining
it, you try to create the complete, finished, product in one long
touchdown pass.  As far as I know, this is a
recipe for disaster.  Countless startups destroyed themselves this
way during the Internet bubble.  I've never heard of a case
where it worked.What people outside the software world may not realize is that
Worse is Better is found throughout the arts.
In drawing, for example, the idea was discovered during the
Renaissance.  Now almost every drawing teacher will tell you that
the right way to get an accurate drawing is not to
work your way slowly around the contour of an object, because errors will
accumulate and you'll find at the end that the lines don't meet.
Instead you should draw a few quick lines in roughly the right place,
and then gradually refine this initial sketch.In most fields, prototypes
have traditionally been made out of different materials.
Typefaces to be cut in metal were initially designed  
with a brush on paper.  Statues to be cast in bronze   
were modelled in wax.  Patterns to be embroidered on tapestries
were drawn on paper with ink wash.  Buildings to be
constructed from stone were tested on a smaller scale in wood.What made oil paint so exciting, when it
first became popular in the fifteenth century, was that you
could actually make the finished work from the prototype.
You could make a preliminary drawing if you wanted to, but you
weren't held to it; you could work out all the details, and
even make major changes, as you finished the painting.You can do this in software too.  A prototype doesn't have to
be just a model; you can refine it into the finished product.
I think you should always do this when you can.  It lets you
take advantage of new insights you have along the way.  But
perhaps even more important, it's good for morale.Morale is key in design.  I'm surprised people
don't talk more about it.  One of my first
drawing teachers told me: if you're bored when you're
drawing something, the drawing will look boring.
For example, suppose you have to draw a building, and you
decide to draw each brick individually.  You can do this
if you want, but if you get bored halfway through and start
making the bricks mechanically instead of observing each one,   
the drawing will look worse than if you had merely suggested
the bricks.Building something by gradually refining a prototype is good
for morale because it keeps you engaged.  In software, my  
rule is: always have working code.  If you're writing
something that you'll be able to test in an hour, then you
have the prospect of an immediate reward to motivate you.
The same is true in the arts, and particularly in oil painting.
Most painters start with a blurry sketch and gradually
refine it.
If you work this way, then in principle
you never have to end the day with something that actually
looks unfinished.  Indeed, there is even a saying among
painters: "A painting is never finished, you just stop
working on it."  This idea will be familiar to anyone who
has worked on software.Morale is another reason that it's hard to design something
for an unsophisticated user.   It's hard to stay interested in
something you don't like yourself.  To make something  
good, you have to be thinking, "wow, this is really great,"
not "what a piece of shit; those fools will love it."Design means making things for humans.  But it's not just the
user who's human.  The designer is human too.Notice all this time I've been talking about "the designer."
Design usually has to be under the control of a single person to
be any good.   And yet it seems to be possible for several people
to collaborate on a research project.  This seems to
me one of the most interesting differences between research and
design.There have been famous instances of collaboration in the arts,
but most of them seem to have been cases of molecular bonding rather
than nuclear fusion.  In an opera it's common for one person to
write the libretto and another to write the music.   And during the Renaissance, 
journeymen from northern
Europe were often employed to do the landscapes in the
backgrounds of Italian paintings.  But these aren't true collaborations.
They're more like examples of Robert Frost's
"good fences make good neighbors."  You can stick instances
of good design together, but within each individual project,
one person has to be in control.I'm not saying that good design requires that one person think
of everything.  There's nothing more valuable than the advice
of someone whose judgement you trust.  But after the talking is
done, the decision about what to do has to rest with one person.Why is it that research can be done by collaborators and  
design can't?  This is an interesting question.  I don't 
know the answer.  Perhaps,
if design and research converge, the best research is also
good design, and in fact can't be done by collaborators.
A lot of the most famous scientists seem to have worked alone.
But I don't know enough to say whether there
is a pattern here.  It could be simply that many famous scientists
worked when collaboration was less common.Whatever the story is in the sciences, true collaboration
seems to be vanishingly rare in the arts.  Design by committee is a
synonym for bad design.  Why is that so?  Is there some way to
beat this limitation?I'm inclined to think there isn't-- that good design requires
a dictator.  One reason is that good design has to   
be all of a piece.  Design is not just for humans, but
for individual humans.  If a design represents an idea that  
fits in one person's head, then the idea will fit in the user's
head too.Related: