ALAN
J.
PERLIS
THE PROGRAMMING LANGUAGES OF THE FUTURE
WILL BE STRANGER
THAN
WE
CAN
IMAGINE
ROLE
OF
LANGUAGE IN PROBLEM
SOLVING-I
Robert Jernigan, Bruce W. Hamill,
and
David M. Weintraub
(Editors), The Johns Hopkins University
Applied Physics Laboratory
Published by North-Holland Publishing Co., Amsterdam, 1985,
405 pp., $55.50
This book contains the edited proceedings
of
a meet-
ing whose concern was that
of
the book's titl:. The
meeting, sponsored by APL, concentrated
at~entlon
~n
computer programming languages and
~h:Ir
~oles
III
solving problems on computers. The specializatlon
was
crucial and everything in the volume must be evaluated
relativ~
to it. There has already appeared in this jour-
nal an excellent review
of
the meeting, listing the titles
and intents
of
the individual presentations and panel
meetings
(B.
W. Hamill, "Symposium on the Role
of
Language in Problem Solving," Johns Hopkins
A:L
Tech. Dig.
6,
149-158
(1985». Therefore, my
reVIew
need not include the customary listing
of
contributors
and summaries
of
their papers.
In the book, a number
of
important questions are
raised treated and debated. In this reviewer's opinion,
most
~ere
not
clarified.
It
is
unlikely that a reader in-
terested in the burning issue
of
the conference will fInish
the book and say,
"Aha,
now I know the question and .
I have seen the answer." The book
is
not likely to be-
come an oft-cited reference, but it
is
worth reading be-
cause it epitomizes the insights that most programming
language people have on the topic. Furthermore, scat-
tered throughout the book are a number
of
pithy nug-
gets about programming languages that are worth re-
membering.
While all languages have some common properties,
natural and programming languages are profoundly dif-
ferent. Programming languages may ape English, but
in no way, constructive
or
observable, are they evolv-
ing toward English or French
or
Hindi. The difference
between programming language and natural language
arises from that between sender and receiver when one
is
human and the other
is
machine: Our computers
don't have enough state to capture the dynamics
of
our
thoughts
as
we
progress through the exercise
of
prob-
lem solving (let alone the heroics
of
dissecting emo-
tions). Since programming languages are meant to be
processed on computers, they must share the latter's
limitations. Sadly, programming languages do affect
the way
we
solve problems. One participant kept insist-
Professor Perlis
is
the Eugene Higgins Professor
of
Computer
Sci-
ence at Yale University.
234
ing that
we
need to make our programming languages
more like natural languages. We do, but the debate
should limit itself to the nature
of
the approximation
and not confuse aping with infancy.
Programming languages are far from useless. As the
book testifies eloquently, an enormous range
of
our
thinking does fmd natural expression in these
languag~s,
often in ways superior to those
we
would have used
III
purely human commerce. Programming languages are
evolving and improving. They are far more than nota-
tions and
we
have a variety to choose from when prob-
lem ;olving. In many cases, the choice
of
language.
is
dominated by social and economic issues more than lin-
guistic ones. People being what they are, hi.story and
traffic have created an honest-to-goodness tnbal struc-
ture partitioned by zealous worship
of
our own pro-
gramming language. This book contains the usual chest-
beating chants (expressed in intellectual terms, to be
sure) asserting the superiority
of
my language over
yours. FORTRAN, APL, LISP, Ada, COBOL, and
PROLOG are all mentioned fondly, and the reader who
seeks knowledge
of
their advantages at the problem-
solving level will find the book a good source.
When
we
solve problems,
we
do so within the frame-
work
of
a symbolic model that may emerge
as
part
of
the solution or,
as
is
usually the case, may be one that
is
already established within the community. The latter
is
usually preferred because some
of
the work
of
tra~s
lation can be bypassed. In his paper, Carlton-Foss il-
lustrates some
of
the models employed in physics. Inso-
far
as
the computer
is
used in problem solving within
a model,
we
seek programming languages that fit the
model's computational needs. Physics supports
so
many
rich models that FORTRAN has gained wide accept-
ance among physicists, not because it affects our think-
ing but because it
doesn't-it
is
neutral and primitive.
Thoughts are not communicated in FORTRAN,
bu~
the
translation into FORTRAN programs
of
computatIOns
arising from within models
is
usually straightforward
though tedious. There
is
a dark side
to
this "thought-
less" use
of
FORTRAN:
It
has prevented the diffusion
into physics
of
the models arising from the complexity
of
computation itself. Only within the last half decade
have such models become a major tool in the study
of
collective phenomena. Complexity itself
is
everyWhere
in science, and the computer, host to an expanding uni-
verse
of
communicating programs,
is
the natural en-
vironment for its study.
If
dependency on FORTRAN
is
harmful, what
is
beneficial? In his paper, Boudreaux reveals his discov-
ery
of
LISP in terms much like Balboa's on seeing the
Johns Hopkins
APL
Technical Digest, Volume
7,
Number 2 (1986)
