This article has multiple issues. Please help improve it or discuss these issues on the talk page. (Learn how and when to remove these template messages)(Learn how and when to remove this template message)
It includes embedded SQL, a report writer language, a form language, and a limited set of imperative capabilities (functions, if and while statements, and supports arrays etc.). The language is particularly close to a natural language and is easy to learn and use.
It has two versions of compiler which either produce 1) intermediate byte code for an interpreter (known as the rapid development system), or 2) C Programming Language code for compilation with a C compiler into machine-code (which executes faster, but compiles slower, and executables are bigger). It is specifically designed to run as a client on a network, connected to an IBM Informix database engine service. It has a mechanism for calling C Programming Language functions and conversely, to be called from executing C programs. The RDS version also features an interactive debugger for Dumb terminals. A particular feature is the comprehensive error checking which is built into the final executable and the extremely helpful error messages produced by both compilers and executables. It also features embedded modal statements for changing compiler and executable behaviour (e.g. causing the compiler to include memory structures matching database schema structures and elements, or to continue executing in spite of error conditions, which can be trapped later on).
The Informix-4GL project was started in 1985, with Chris Maloney as chief architect. Roy Harrington was in charge of the related Informix Turbo (later renamed Online) engine, which bypassed the "cooked" file system in favour of "raw" disk. A Rapid Application Development Tool called FourGen CASE Tools, was bundled with Informix-4GL from 1989 to 1996. Another flavor of Informix programming-tool was produced, called "NewEra", which supported object-oriented programming and a level of code-compatibility with Informix-4GL.
Informix was acquired by IBM in April 2001.
Despite its age, Informix-4GL is still widely used to develop business applications, and a sizable market exists around it due to its popularity. With accounting being an inherently text based activity, it is often chosen for its purely text-based interface to optimize data entry efficiency. New accounting applications are still being developed with Informix-4GL for this reason, such as Stansoft which was released in 2010. The Eppix telecommunication accounting system uses IBM Tuxedo services written in the C Programming Language to call pre-compiled 4GL object modules dynamically at run-time.