Modula-2

Modula-2 is a computer programming language invented by Niklaus Wirth at ETH in 1978. It is a derivative of an earlier version, simply called Modula, which was itself largely based on Wirth's earlier language, Pascal. Modula-2 was designed to be broadly similar to to Pascal, with some elements removed and the important addition of the module concept, and facilities for parallel computation.

The central concept of Modula-2 is the module, which may be used to encapsulate a set of related subprograms and data structures, and restrict their visibility from other portions of the program. Modula-2 programs are made up of two parts: a definition module, the interface portion, which contains only those parts of the subsystem that are visible to other modules, and an implementation module, which contains the working code that is internal to the module.

The language provides limited single-processor concurrency (monitors, coroutines and explicit transfer of control) and hardware access (absolute addresses and interrupts). It uses name equivalence.

Although Modula-2 is by far the best-known and most widely used variant, there are several related languages: the original Modula, Modula-2+, Modula-2*, Modula-3, Oberon, Oberon-2, and a number of others. These are not "later versions" or "replacements" for Modula-2, they are different languages with different purposes, with strengths and weaknesses of their own. Along with C and Ada, Modula-2 is often regarded as one of the three "modern" programming languages. Of the three, Modula-2 is the smallest and the easiest to read.

Modula-2 was developed as the system language for the Lilith[?] workstation, and formed the basis of Oberon. Most current programming languages have adopted many of the features of Modula-2.

External Links

• Official website (http://www.modula2.org/)

Credit This article is based on material from FOLDOC, used with permission. Update as needed.