COMPUTER PROGRAMME

Advantages and disadvantages of each generation of language

• Readability of the language
 If parts of the program are going to be read or altered separately form the entire program is might be worth considering how legible they are going to be. Clumsy abbreviations should be avoided. Statements such as WHILE LOOP have increased the readability of programs and lead to neater programs.

• Ease of writing the language
 A programming language that is easy to write in can make the process easier and faster. It may help to reduce mistakes, save time and money, and make the program smaller.

• Reliability of the language
 A program that is not robust can cause errors, and code can “decay”. Any language that helps the programmer to avoid mistakes will make it easier to use.

• Cost of development
 Is the language expensive to use and to maintain? Program may need to be updated or re-developed and an expensive language may make this prohibitive.

• Syntax complexity
 Syntax is an important consideration. Clarity and ease of understanding are important, as is a syntax that seems logical and sensible. Errors are very likely to occur where one area of syntax too closely resembles another, and the program may prove difficult to debug.

• Language standards
 Languages that have standards for writing programs have greater readability.

Language Models

• Imperative Languages – are formed from collections of basic commands, most often assignments and I/O, where the execution is sequenced by control structures.

• Functional Languages – are based on lambda-calculus from the 1930’s. Programs consist of collections of function definitions and function applications.


• Logic Programming – consists of collections of statements within a particular logic. Most typically that logic is predicate logic. ProLog.

• Object-oriented languages – Programs consist of objects that interact with each other. Some also associate inheritance and polymorphism with OO language. Smalltalk, Java.

• Declarative languages – are collections of declarations. Many functional and logic languages are also declarative. Declarative languages describe relationships between variables in terms of functions or inference rules and the language executor applies some fixed algorithm to these relations to produce a result.

• Scripting language – work in conjunction with a larger application, support control of a variety of applications, are interpreted, or some combination thereof.

• Parallel language – are collections of processes that communicate with each other.