Gforth
Overview
Gforth is a free implementation of the Forth programming language. It was developed as part of the GNU Project, and is therefore also known as GNU Forth. Gforth runs on many systems, from embedded platforms to desktops and servers. Its kernel is written in C, and the rest of the engine is implemented in Forth.
History
Gforth was first released in 1995 by the Free Software Foundation. It was developed to provide a free and open-source Forth environment that adheres to the ANS Forth standard. The project has been actively maintained since its inception, with the latest stable release being version 0.7.9, released in December 2018.
Design and Implementation
Gforth is designed to be portable across a wide range of systems. Its kernel is written in C, which allows it to run on any platform that has a C compiler. The rest of the system, including the compiler, the interpreter, and most of the standard library, is written in Forth. This design allows Gforth to take full advantage of the unique features of the Forth language, such as its extensibility and its support for interactive development.
Gforth uses a direct-threaded code (DTC) approach for its implementation. This means that the compiled code consists of a sequence of addresses, each pointing to a piece of code that implements a Forth word (a function or subroutine in other languages). This approach makes the compiled code compact and fast, but it also means that the performance of Gforth programs is highly dependent on the quality of the system's C compiler and linker.
Features
Gforth supports most of the ANS Forth core word set, as well as many of the optional word sets defined by the standard. It also provides several extensions to the standard, including support for exception handling, multitasking, and object-oriented programming.
Gforth's interactive development environment includes a command-line interface (CLI) that provides immediate feedback, a feature that is characteristic of Forth systems. The CLI allows users to define new words, execute commands, and inspect the system's state at any time. Gforth also includes a source-level debugger and a profiler, which can be used to analyze and optimize Forth programs.
Usage
Gforth can be used for a wide range of applications, from low-level system programming to high-level scripting. It is particularly well-suited for tasks that require direct control over the hardware, such as embedded systems development. However, its interactive nature and its high-level features also make it a powerful tool for rapid prototyping and exploratory programming.
To install Gforth, users can download the source code from the GNU Project's website and compile it on their system. Precompiled binaries are also available for some platforms. Once installed, Gforth can be started from the command line, and Forth code can be loaded into the system using the 'include' command.