4GLs

4GLs, or fourth-generation programming languages, are a class of high-level tools designed to raise developer productivity by letting users specify desired results rather than step-by-step procedures. They are typically more abstract than traditional third-generation languages and are often tailored to particular domains such as databases, reports, or data analysis.

Key characteristics include declarative or rule-based syntax, domain-specific constructs, and integrated development environments that provide designers and prebuilt components. Many 4GLs emphasize what to accomplish over how to accomplish it, and often hide implementation details such as data access, indexing, and optimization from the user.

Common examples and categories include SQL and query-by-example interfaces for data retrieval, report generators, and data-manipulation languages used in business analytics. Other widely cited 4GLs include MATLAB, SAS, SPSS, ABAP, and Informix-4GL, as well as form and report tools in application development environments.

Historically, the term arose in the 1970s and 1980s as vendors sought to commodify software development with higher-level abstractions. Over time, many 4GL capabilities have been absorbed into more general-purpose languages and modern rapid development platforms, blurring the boundaries between generations.

Limitations of 4GLs can include less control over performance, potential vendor lock-in, and reduced flexibility for low-level tasks. They remain best suited for well-defined, data-centric tasks such as querying databases, generating reports, and building business applications with rapid iteration.