fourth generation language

language (4GL) An "application specific" language, one with

built-in knowledge of an application domain, in the way that

SQL has built-in knowledge of the database domain. Pure

4GLs do not contain conditionals (if-then-else) and loops

(for, while, do), though some languages are combinations of

third generation languages and 4GLs.

The term was invented by Jim Martin to refer to

non-procedural high level languages built around

database systems. The first three generations were

developed fairly quickly, but it was still frustrating, slow,

and error prone to program computers, leading to the first

"programming crisis", in which the amount of work that might

be assigned to programmers greatly exceeded the amount of

programmer time available to do it. Meanwhile, a lot of

experience was gathered in certain areas, and it became clear

that certain applications could be generalised by adding

limited programming languages to them. Thus were born reportgenerator languages, which were fed a description of the data

format and the report to generate and turned that into a

COBOL (or other language) program which actually contained

the commands to read and process the data and place the

results on the page.

Some other successful 4th-generation languages are: databasequery languages, e.g. SQL; Focus, Metafont,

PostScript, RPG-II, S, IDL-PV/WAVE, Gauss,

Mathematica; and data-stream languages such as AVS,

APE, Iris Explorer.

(2003-07-29)