Java Reference
In-Depth Information
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ANDOM
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ACT
9.2: Programming Languages
Many hundreds of programming languages exist today, which is actually quite
surprising. The idea behind a high-level programming language is to provide a
medium for programming that is independent from the instruction set of a
particular processor, so that one can move programs from one computer to another
without rewriting them. Moving a program from one programming language to
another is a difficult process, however, and it is rarely done. Thus, it seems that
there would be little use for so many programming languages.
Unlike human languages, programming languages are created with specific
purposes. Some programming languages make it particularly easy to express tasks
from a particular problem domain. Some languages specialize in database
processing; others in Ȓartificial intelligenceȓ programs that try to infer new facts
from a given base of knowledge; others in multimedia programming. The Pascal
language was purposefully kept simple because it was designed as a teaching
language. The C language was developed to be translated efficiently into fast
machine code, with a minimum of housekeeping overhead. The C++ language
builds on C by adding features for object-oriented programming. The Java
language was designed for securely deploying programs across the Internet.
In the early 1970s the U.S. Department of Defense (DoD) was seriously concerned
about the high cost of the software components of its weapons equipment. It was
estimated that more than half of the total DoD budget was spent on the
development of this embedded-systems softwareȌthat is, software that is
embedded in some machinery, such as an airplane or missile, to control it. One of
the perceived problems was the great diversity of programming languages that
were used to produce that software. Many of these languages, such as TACPOL,
CMS-2, SPL/1, and JOVIAL, were virtually unknown outside the defense sector.
In 1976 a committee of computer scientists and defense industry representatives
was asked to evaluate existing programming languages. The committee was to
determine whether any of them could be made the DoD standard for all future
military programming. To nobody's surprise, the committee decided that a new
language would need to be created. Contractors were then invited to submit
designs for such a new language. Of 17 initial proposals, four were chosen to
