OT; Donald Knuth on beauty, efficiency, and the programmer as artist

[Laeeth Isharc via Digitalmars-d-learn]

An old essay that may yet be relevant today at a time when 
intellectual fashion has continued in the direction he was moved 
to address in his speech.

"there is a way to make a big improvement: it is still a pleasure 
to do routine jobs if we have beautiful things to work with. For 
example, a person will really enjoy wiping off the dining room 
table, day after day, if it is a beautifully designed table made 
from some fine quality hardwood."

"Language designers also have an obligation to provide languages 
that encourage good style, since we all know that style is 
strongly influenced by the language in which it is expressed. The 
present surge of interest in structured programming has revealed 
that none of our existing languages is really ideal for dealing 
with program and data structure"

http://www.paulgraham.com/knuth.html

CACM, December 1974

When Communications of the ACM began publication in 1959, the 
members of ACM'S Editorial Board made the following remark as 
they described the purposes of ACM'S periodicals [2]:
"If computer programming is to become an important part of 
computer research and development, a transition of programming 
from an art to a disciplined science must be effected."
Such a goal has been a continually recurring theme during the 
ensuing years; for example, we read in 1970 of the "first steps 
toward transforming the art of programming into a science" [26]. 
Meanwhile we have actually succeeded in making our discipline a 
science, and in a remarkably simple way: merely by deciding to 
call it "computer science."

Implicit in these remarks is the notion that there is something 
undesirable about an area of human activity that is classified as 
an "art"; it has to be a Science before it has any real stature. 
On the other hand, I have been working for more than 12 years on 
a series of books called "The Art of Computer Programming." 
People frequently ask me why I picked such a title; and in fact 
some people apparently don't believe that I really did so, since 
I've seen at least one bibliographic reference to some books 
called "The Act of Computer Programming."

In this talk I shall try to explain why I think "Art" is the 
appropriate word. I will discuss what it means for something to 
be an art, in contrast to being a science; I will try to examine 
whether arts are good things or bad things; and I will try to 
show that a proper viewpoint of the subject will help us all to 
improve the quality of what we are now doing.
...
As I was looking up these things about the meanings of "art," I 
found that authors have been calling for a transition from art to 
science for at least two centuries. For example, the preface to a 
textbook on mineralogy, written in 1784, said the following [17]: 
"Previous to the year 1780, mineralogy, though tolerably 
understood by many as an Art, could scarce be deemed a Science."

According to most dictionaries "science" means knowledge that has 
been logically arranged and systematized in the form of general 
"laws." The advantage of science is that it saves us from the 
need to think things through in each individual case; we can turn 
our thoughts to higher-level concepts. As John Ruskin wrote in 
1853 [32]: "The work of science is to substitute facts for 
appearances, and demonstrations for impressions."

It seems to me that if the authors I studied were writing today, 
they would agree with the following characterization: Science is 
knowledge which we understand so well that we can teach it to a 
computer; and if we don't fully understand something, it is an 
art to deal with it. Since the notion of an algorithm or a 
computer program provides us with an extremely useful test for 
the depth of our knowledge about any given subject, the process 
of going from an art to a science means that we learn how to 
automate something.
...
 From this standpoint it is certainly desirable to make computer 
programming a science, and we have indeed come a long way in the 
15 years since the publication ot the remarks I quoted at the 
beginning of this talk. Fifteen years ago computer programming 
was so badly understood that hardly anyone even thought about 
proving programs correct; we just fiddled with a program until we 
"knew" it worked. At that time we didn't even know how to express 
the concept that a program was correct, in any rigorous way. It 
is only in recent years that we have been learning about the 
processes of abstraction by which programs are written and 
understood; and this new knowledge about programming is currently 
producing great payoffs in practice, even though few programs are 
actually proved correct with complete rigor, since we are 
beginning to understand the principles of program structure.
...
A scientific approach is generally characterized by the words 
logical, systematic, impersonal, calm, rational, while an 
artistic approach is characterized by the words aesthetic, 
creative, humanitarian, anxious, irrational. It seems to me that 
both of these apparently contradictory approaches have great 
value with respect to computer programming.
...
When I speak about computer programming as an art, I am thinking 
primarily of it as an art form, in an aesthetic sense. The chief 
goal of my work as educator and author is to help people learn 
how to write beautiful programs. It is for this reason I was 
especially pleased to learn recently [32] that my books actually 
appear in the Fine Arts Library at Cornell University. (However, 
the three volumes apparently sit there neatly on the shelf, 
without being used, so I'm afraid the librarians may have made a 
mistake by interpreting my title literally.)

My feeling is that when we prepare a program, it can be like 
composing poetry or music; as Andrei Ershov has said [9], 
programming can give us both intellectual and emotional 
satisfaction, because it is a real achievement to master 
complexity and to establish a system of consistent rules.

Furthermore when we read other people's programs, we can 
recognize some of them as genuine works of art. I can still 
remember the great thrill it was for me to read the listing of 
Stan Poley's SOAP II assembly program in 1958; you probably think 
I'm crazy, and styles have certainly changed greatly since then, 
but at the time it meant a great deal to me to see how elegant a 
system program could be, especially by comparison with the 
heavy-handed coding found in other listings I had been studying 
at the same time. The possibility of writing beautiful programs, 
even in assembly language, is what got me hooked on programming 
in the first place.

Some programs are elegant, some are exquisite, some are 
sparkling. My claim is that it is possible to write grand 
programs, noble programs, truly magnificent ones!
..
Another important aspect of program quality is the efficiency 
with which the computer's resources are actually being used. I am 
sorry to say that many people nowadays are condemning program 
efficiency, telling us that it is in bad taste. The reason for 
this is that we are now experiencing a reaction from the time 
when efficiency was the only reputable criterion of goodness, and 
programmers in the past have tended to be so preoccupied with 
efficiency that they have produced needlessly complicated code; 
the result of this unnecessary complexity has been that net 
efficiency has gone down, due to difficulties of debugging and 
maintenance.

The real problem is that programmers have spent far too much time 
worrying about efficiency in the wrong places and at the wrong 
times; premature optimization is the root of all evil (or at 
least most of it) in programming.

We shouldn't be penny wise and pound foolish, nor should we 
always think of efficiency in terms of so many percent gained or 
lost in total running time or space. When we buy a car, many of 
us are almost oblivious to a difference of $50 or $100 in its 
price, while we might make a special trip to a particular store 
in order to buy a 50 cent item for only 25 cents. My point is 
that there is a time and place for efficiency; I have discussed 
its proper role in my paper on structured programming, which 
appears in the current issue of Computing Surveys [21].
...
One rather curious thing I've noticed about aesthetic 
satisfaction is that our pleasure is significantly enhanced when 
we accomplish something with limited tools. For example, the 
program of which I personally am most pleased and proud is a 
compiler I once wrote for a primitive minicomputer which had only 
4096 words of memory, 16 bits per word. It makes a person feel 
like a real virtuoso to achieve something under such severe 
restrictions.
...
When we teach programming nowadays, it is a curious fact that we 
rarely capture the heart of a student for computer science until 
he has taken a course which allows "hands on" experience with a 
minicomputer. The use of our large-scale machines with their 
fancy operating systems and languages doesn't really seem to 
engender any love for programming, at least not at first.
...
How did they develop their skill? The best film makers through 
the years usually seem to have learned their art in comparatively 
primitive circumstances, often in other countries with a limited 
movie industry. And in recent years the most important things we 
have been learning about programming seem to have originated with 
people who did not have access to very large computers. The moral 
of this story, it seems to me, is that we should make use of the 
idea of limited resources in our own education. We can all 
benefit by doing occasional "toy" programs, when artificial 
restrictions are set up, so that we are forced to push our 
abilities to the limit. We shouldn't live in the lap of luxury 
all the time, since that tends to make us lethargic.
...
In a similar vein, we shouldn't shy away from "art for art's 
sake"; we shouldn't feel guilty about programs that are just for 
fun. I once got a great kick out of writing a one-statement ALGOL 
program that invoked an innerproduct procedure in such an unusual 
way that it calculated the mth prime number, instead of an 
innerproduct [19]. Some years ago the students at Stanford were 
excited about finding the shortest FORTRAN program which prints 
itself out, in the sense that the program's output is identical 
to its own source text.
...
Another characteristic of modern art is its emphasis on 
creativity. It seems that many artists these days couldn't care 
less about creating beautiful things; only the novelty of an idea 
is important. I'm not recommending that computer programming 
should be like modern art in this sense, but it does lead me to 
an observation that I think is important. Sometimes we are 
assigned to a programming task which is almost hopelessly dull, 
giving us no outlet whatsoever for any creativity; and at such 
times a person might well come to me and say, "So programming is 
beautiful? It's all very well for you to declaim that I should 
take pleasure in creating elegant and charming programs, but how 
am I supposed to make this mess into a work of art?"

Well, it's true, not all programming tasks are going to be fun. 
Consider the "trapped housewife," who has to clean off the same 
table every day: there's not room for creativity or artistry in 
every situation. But even in such cases, there is a way to make a 
big improvement: it is still a pleasure to do routine jobs if we 
have beautiful things to work with. For example, a person will 
really enjoy wiping off the dining room table, day after day, if 
it is a beautifully designed table made from some fine quality 
hardwood.
...
Therefore I want to address my closing remarks to the system 
programmers and the machine designers who produce the systems 
that the rest of us must work with. Please, give us tools that 
are a pleasure to use, especially for our routine assignments, 
instead of providing something we have to fight with. Please, 
give us tools that encourage us to write better programs, by 
enhancing our pleasure when we do so.

It's very hard for me to convince college freshmen that 
programming is beautiful, when the first thing I have to tell 
them is how to punch "slash slash JoB equals so-and-so." Even job 
control languages can be designed so that they are a pleasure to 
use, instead of being strictly functional.
...
  Some tasks are best done by machine, while others are best done 
by human insight; and a properly designed system will find the 
right balance. (I have been trying to avoid misdirected 
automation for many years, cf. [18].)
...
Language designers also have an obligation to provide languages 
that encourage good style, since we all know that style is 
strongly influenced by the language in which it is expressed. The 
present surge of interest in structured programming has revealed 
that none of our existing languages is really ideal for dealing 
with program and data structure, nor is it clear what an ideal 
language should be. Therefore I look forward to many careful 
experiments in language design during the next few years.
...
We have seen that computer programming is an art, because it 
applies accumulated knowledge to the world, because it requires 
skill and ingenuity, and especially because it produces objects 
of beauty. A programmer who subconsciously views himself as an 
artist will enjoy what he does and will do it better. Therefore 
we can be glad that people who lecture at computer conferences 
speak about the state of the Art.
====
https://www.simple-talk.com/opinion/opinion-pieces/don-knuth-and-the-art-of-computer-programming-the-interview/

I think of a programming language as a tool to convert a 
programmer's mental images into precise operations that a machine 
can perform. The main idea is to match the user's intuition as 
well as possible. There are many kinds of users, and many kinds 
of application areas, so we need many kinds of languages.

...
I realise this is an enormous question, but what is the link 
between the design of a language and the design of software 
written with that language?
DK:
The software writers who have particular ways of thinking about 
algorithms need a language that matches their thoughts so that 
they can efficiently transform those thoughts into working code.

Different thought processes result in different structures.