Programming Domains

Computers have been applied to a myriad of different areas, from controlling
nuclear power plants to providing video games in mobile phones. Because of
this great diversity in computer use, programming languages with very different
goals have been developed.
Lets  briefly discuss a few of the areas of computer applications and their associated languages.



                                               Scientific Applications

The first digital computers, which appeared in the late 1940s and early 1950s,
were invented and used for scientific applications. Typically, the scientific applications of that time used relatively simple data structures, but required large numbers of floating-point arithmetic computations.

• The most common data structures were arrays and matrices; 
• the most common control structures were counting loops and selections.

The early high-level programming languages invented for scientific applications were designed to provide for those needs.
Their competition was assembly language, so efficiency was a primary concern.
The first language for scientific applications was Fortran.
ALGOL 60 and most of its descendants were also intended to be used in this area, although they were designed to be used in related areas as well.

For some scientific applications where efficiency is the primary concern, such as those that were common in the 1950s and 1960s, no subsequent language is significantly better than Fortran, which explains why Fortran is still used.

                                                Business Applications

The use of computers for business applications began in the 1950s. Special
computers were developed for this purpose, along with special languages. The
first successful high-level language for business was COBOL(ISO/IEC, 2002),
the initial version of which appeared in 1960.
It is still the most commonly used language for these applications.

Business languages are characterized by facilities for producing elaborate reports, precise ways of describing and storing decimal numbers and character data, and the ability to specify decimal arithmetic operations.

There have been few developments in business application languages outside the development and evolution of COBOL.


                                                 Artificial Intelligence

Artificial intelligence (AI) is a broad area of computer applications characterized by the use of symbolic rather than numeric computations.

• Symbolic computation means that symbols, consisting of names rather than numbers, are manipulated. 
• Also, symbolic computation is more conveniently done with linked lists of data rather than arrays. This kind of programming sometimes requires more flexibility than other programming domains. For example, in some AI applications the ability to create and execute code segments during execution is convenient.

The first widely used programming language developed for AI applications was the functional language LISP (McCarthy et al., 1965), which appeared in 1959. Most AI applications developed prior to 1990 were written in LISP or one of its close relatives. Scheme (Dybvig, 2003), a dialect of LISP
During the early 1970s, however, an alternative approach to some of these applications appeared—logic programming using the Prolog (Clocksin and Mellish, 2003) language. More recently, some AI applications have been written in systems languages such as C.


                                               Systems Programming

The operating system and the programming support tools of a computer system are collectively known as its systems software.

• Systems software is used almost continuously and so it must be efficient.
•  Furthermore, it must have low-level features that allow the software interfaces to external devices to be written.

In the 1960s and 1970s, some computer manufacturers, such as IBM, Digital, and Burroughs (now UNISYS), developed special machine-oriented high-level languages for systems software on their machines.

• For IBM mainframe computers, the language was PL/S, a dialect of PL/I; 
• for Digital (DEC), it was BLISS, a language at a level just above assembly language; 
• for Burroughs, it was Extended ALGOL. 
• However, most system software is now written in more general programming languages, such as C and C++.
• The UNIX operating system is written almost entirely in C (ISO, 1999), which has made it relatively easy to port, or move, to different machines. 

Some of the characteristics of C make it a good choice for systems programming.

• It is low level, 
• execution efficient, and 
• does not burden the user with many safety restrictions. Systems programmers are often excellent programmers who believe they do not need such restrictions. 
• Some nonsystems programmers, however, find C to be too dangerous to use on large, important software systems.

                                                          Web Software

The World Wide Web is supported by an eclectic collection of languages,
ranging from markup languages, such as HTML, which is not a programming
language, to general-purpose programming languages, such as Java.

Because of the pervasive need for dynamic Web content, some computation capability is often included in the technology of content presentation.
This functionality can be provided by embedding programming code in an HTML document.
Such code is often in the form of a scripting language, such as JavaScript or
PHP. There are also some markup-like languages that have been extended to
include constructs that control document processing.