8/7/2019 The Object

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The object-oriented nature of LISP and PROLOG enables each to be applied within the context of the

prototyping paradigm for software engineering.

APL is an extremely concise and powerful language for array and vector manipulation. The language

contains little support for structured constructs or data typing. APL does provide a rich set of

computational operators and has gained a small but avid following for mathematical problem solving.

FORTH is a language designed for microprocessor software development. The language supports the

definition of user- defined functions [implemented with post-fix (reverse-polish)notation] that are

executed in stack-oriented manner for speed and memory efficiency.

From a software engineering standpoint, specialized languages provide both advantages and

disadvantages. Because a specialized language has been designed to address a specific application, the

translation of requirements to design to code implementation can be facilitated. On the other hand,

most specialized languages are far less portable and often less maintainable than general-purpose

languages.

Fourth-Generation Languages

Throughout the history of software development, we have attempted to generation computer programs

at higher and higher levels of abstraction. First generation programming languages worked at machine

instruction set level, the lowest possible level of abstraction. Second- and third-generation

programming. Languages have raised the level at which we represent computer programs, but distinct

and completely detailed algorithmic procedures still have to be specified. Over the past decade, fourth-

generation languages (4GLs) have raised the level of abstraction still higher.

fourth-generation languages, like all artificial languages, contain a distinct syntax for control and data

structure representation. A 4GL, however, represent these structures at higher level of abstraction by

eliminating the need to specify algorithmic detail. For example, the statement:

COMPUTE NET-PRESENT-VALUE AND RETURN-ON- INVESTMENT FOR EXPENDITURES #5 AND #9.

Is typical of a 4GL statement. The $GL system knows how to compute the desired financial data and

does so without requiring the software developer to specify the appropriate domain-specific. That is,

the same 4GL would undoubtedly choke on:

COMPUTE THE ROOTS OF TRANSCENDENTAL EQUATION #3 AND APPLY THEM TO THE PHYSICAL MODEL.

Although another 4GL, designed specifically for the application domain implied above, might do the jobnicely.