A fourth-generation programming language (1970s-1990) (abbreviated 4GL) is a programming language or programming environment designed with a specific purpose in mind, such as the development of commercial business software
In the history of computer science, the 4GL followed the 3GL in an upward trend toward higher abstraction and statement power
The 4GL was followed by efforts to define and use a 5GL
The natural-language, block-structured mode of the third-generation programming languages improved the process of software development
3GL development methods can be slow and error-prone. It became clear that some applications could be developed more rapidly by adding a higher-level programming language and methodology which would generate the equivalent of very complicated 3GL instructions with fewer errors
In some senses, software engineering arose to handle 3GL development
4GL and 5GL projects are more oriented toward problem solving and systems engineering
All 4GLs are designed to reduce programming effort, the time it takes to develop software, and the cost of software development. They are not always successful in this task, sometimes resulting in inelegant and unmaintainable code
Given the right problem, the use of an appropriate 4GL can be spectacularly successful as was seen with MARK-IV and MAPPER (see History Section, Santa Fe real-time tracking of their freight cars – the productivity gains were estimated to be 8 times over COBOL)
The usability improvements obtained by some 4GLs (and their environment) allowed better exploration for heuristic solutions than did the 3GL
Fourth-generation languages have often been compared to domain-specific programming languages (DSLs). Some researchers state that 4GLs are a subset of DSLs
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