Speakeasy: an evolutionary system Page: 4 of 10
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creating a system of extreme size and complexity.
At the same time the use of libraries provides the
mechanism for tailoring systems to specific appli-
cations without restricting the overall development.
The extreme modularity of this system, the
extensive use of libraries and the simplicity of its
control language combine to provide a system with
extreme power, ease of adaptability and the capa-
bility for sustained growth.
Ill. DESIGN OF THE I.ANGUAGE
The Speakeary system is a repository for
ideas. The communication language for the sys-
tem (also called Speakeasy) is intended to make
this repository usable. in designing the language
and its syntatical rules the foremost considerations
were naturalness, ease of use and tolerance for
trivial mistakes. The basic specification for the
language is a simple one. I a request by a user is
unambiguous and looks correct to him then it should
be accepted by the system. (For the most part this
specification hks been realized in the cur rent
processors.)
This is somewhat different in philosophy
from normal computer languages that are designed
for programming a caleilation for computer pro-
cessi.g. Such languages are, to a large extent,
tailored to the existing hardware facilities. The
specifications of many conventional languages are
designed so that a large number of decisions that
relate only indirectly to the calculation must be
made by the programmer. To give just a few ex-
amples, fixed point versus floating point number.
dimension statements for quantities that occur only
as inte rmed ate results, and input and output for-
mats-none of these are directly related to the
statement of the problem itself. Often such rela-
tivety trivial specifications constitute the bulk of
a program-the parts of the program related to
the caculation are but a small part of the material
wr.tten by the user.
In Speakeasy mnst of such decisions are
considered to be part of the internal functions of
the system. The user it supposed to formulate
his problem in as brief and as natural a manner
as possible, the system is supposed to translate
this formulation into an executable form, reliev-
ing the user of as many decisions as possible.
Actually the Speakeasy language specifications
bear little relationship to the structure of a com-
puter and only very indirectly reflect the form of
calculation as expected in the computer.
The Speakeasy Isnguage is designed to oper-
ate with structured objects. Arrays of numbers.
mathematical vectors and true matrices are among
the many classes of structured objects that a user
may define and use in his calculations. Implicit
algebraic rules that are class dependent provide avariety of tools for formulating calculations while
operating on defined objects as single entities.
Ths availability of structured objects means
that an ope rator-operand form of language with
great richness can be developed (one of the limita-
tions of a normal language is that the scalar struc-
ture of the language itself limits the availability of
built-in functions to those that operate on scalars).
Each of the operators in Speakeasy is designed as
a self-contained module whose operations are de-
pendent upon the structure of its operands. In this
way all of the decisions normally nerossary in in-
voking routines in conventional programming
techniques are internally contained in the operators
of the system. Each operator is clearly definable
in terms of what it does and contains many checks
to see that it is being properly applied. Dy placing
decision processes such as these within the system
the user is relieved of most of the mundane parts
of programming associated with languages such as
Fortran or PL/1. The user can concentrate his
effort on formulating the overall logic of his com-
putation and be assured thai a vast number Lf deci-
sions are being properly made.
Tolerance is somewhat foreign to computer
languages. A misplaced comma in a format state-
ment in most programming languages results in a
complete abort of the calculation even though the
intent of the user was obvious. In Speakeasy the
primary intent is to provide the user with the an-
swers to his problem, not to force him to specify
his problem within rigid language rules. The
structure of the langune itself makes errors un-
likely and the tolerant analysis aids even more by
ignoring unimportant syntatical errors.
As compensation for the tolerant language a
large amount of internal consistency checking is
carried out for each operation. The presence of
structured objects in the language means that a
large amount of information is available to the
processor and as a result a large number of tests
can be carried out automatically. Checks are
thorough and prevent erroneously formulated prob-
lems from being carried out. Such internal check-
ing combined with the tolerant language syntax
provide the means for quickly and easily formulat-
ing a problem for processing with the assurance
that the overall logic is correct. Actually the
checking process is so detailed that completion of
a problem without a detected error is real assur-
ance of correct logic specification, a feature miss-
ing in most other languages. The overall language
designed around an operator-operand concept
combined with conventional algebraic tools is
powerful, easily learned and easily used. It is
logically complete and is extensibie in both the
types of structure supported, the algebraic rules
for new structures, and the operators available
for operating on objects.3
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Cohen, S. Speakeasy: an evolutionary system, report, January 1, 1974; Illinois. (https://digital.library.unt.edu/ark:/67531/metadc1018559/m1/4/: accessed April 18, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.