ABC is an imperative general-purpose programming language and integrated development environment (IDE) developed at Centrum Wiskunde & Informatica (CWI), in Amsterdam, Netherlands by Leo Geurts, Lambert Meertens, and Steven Pemberton. It is interactive, structured, high-level, and intended to be used instead of BASIC, Pascal, or AWK. It is intended for teaching or prototyping, but not as a systems-programming language.
ABC had a major influence on the design of the language Python, developed by Guido van Rossum, who formerly worked for several years on the ABC system in the mid-1980s.
Features
Its designers claim that ABC programs are typically around a quarter the size of the equivalent Pascal or C programs, and more readable.4 Key features include:
- Only five basic data types
- No required variable declarations
- Explicit support for top-down programming
- Statement nesting is indicated by indentation, via the off-side rule
- Infinite precision arithmetic, unlimited-sized lists and strings, and other features supporting orthogonality and ease of use by novices
- Polymorphic commands and functions
- Interactive environment with command completion, persistent workspaces, and no separate file handling
ABC was originally a monolithic implementation, leading to an inability to adapt to new requirements, such as creating a graphical user interface (GUI). ABC could not directly access the underlying file system and operating system.
The full ABC system includes a programming environment with a structure editor (syntax-directed editor), suggestions, static variables (persistent), and multiple workspaces, and is available as an interpreter–compiler. As of 2020[update], the latest version is 1.05.02, and it is ported to Unix, DOS, Atari, and Apple MacOS.
Example
An example function to collect the set of all words in a document:5
HOW TO RETURN words document: PUT {} IN collection FOR line IN document: FOR word IN split line: IF word not.in collection: INSERT word IN collection RETURN collectionImplementations
ABC has been through multiple iterations, with the current version being the 4th major release. Implementations exist for Unix-like systems, MS-DOS/Windows, Macintosh, and other platforms. The source code was made available via Usenet in the late 1980s/early 1990s.
Further reading
More details on ABC can be found in the book "The ABC Programmer's Handbook" by Leo Geurts, Lambert Meertens and Steven Pemberton (ISBN 0-13-000027-2). A newsletter and mailing list were available from CWI.
External links
References
Pemberton, Steven (January 1987). "An Alternative Simple Language and Environment for PCs". IEEE Software. 4 (1): 56–64. doi:10.1109/MS.1987.229797. S2CID 12788361. /wiki/Steven_Pemberton ↩
Hamilton, Naomi (2008-05-08). "The A-Z of Programming Languages: Python". Computerworld. IDG Communications. Archived from the original on 2008-12-29. Retrieved 2020-09-04. ... I figured I could design and implement a language 'almost, but not quite, entirely unlike' ABC, improving upon ABC's deficiencies, ... https://web.archive.org/web/20081229095320/http://www.computerworld.com.au/index.php/id%3B66665771 ↩
Stewart, Bruce (2002-06-04). "An Interview with Guido van Rossum". ONLamp.com. O’Reilly Media. Archived from the original on 2013-03-13. Retrieved 2020-09-04. ... in my head I had analyzed some of the reasons it had failed. https://web.archive.org/web/20130313095540/http://www.onlamp.com/pub/a/python/2002/06/04/guido.html ↩
Pemberton, Steven (2012-02-22). "The ABC Programming Language: a short introduction". Centrum Wiskunde & Informatica (CWI). Amsterdam. Retrieved 2020-09-04. https://homepages.cwi.nl/~steven/abc/ ↩
This article is based on material taken from ABC at the Free On-line Dictionary of Computing prior to 1 November 2008 and incorporated under the "relicensing" terms of the GFDL, version 1.3 or later. https://foldoc.org/ABC ↩