Editing ABC (programming language)

{{Short description|Programming language}}
{{Infobox programming language
|name = ABC
|logo =
|paradigms = [[Multi-paradigm programming language|multi-paradigm]]: [[Imperative programming|imperative]], [[Procedural programming|procedural]], [[Structured programming|structured]]
|designers = Leo Geurts, [[Lambert Meertens]], [[Steven Pemberton]]
|developer = [[Centrum Wiskunde & Informatica]] (CWI)
|released = {{Start date and age|1987|01}}
|latest release version = 1.05.02
|latest release date = {{Start date and age|1990}}<!-- If known, add |mm|dd -->
|typing = [[Strong and weak typing|strong]], [[Polymorphism (computer science)|polymorphic]]
|implementations =
| operating system = [[Unix-like]], [[Windows]], [[MacOS]], and [[Atari TOS]]
|dialects =
|influenced by = [[SETL]], [[ALGOL 68]]<ref>{{cite book |page=32 |url=https://books.google.com/books?q=He-was-clearly-influenced-by-ALGOL-68 |access-date=December 14, 2009 |last1=Biancuzzi |first1=Federico |last2=Warden |first2=Shane |title=Masterminds of Programming: Conversations with the Creators of Major Programming Languages |publisher=[[O'Reilly Media]] |date=April 2009 |isbn=978-0-596-51517-1 |quote=He [Lambert Meertens] was clearly influenced by [[ALGOL 68]]'s philosophy of providing constructs that can be combined in many different ways to produce all sorts of different data structures or ways of structuring a program. – [[Guido van Rossum]]}}</ref>
|influenced = [[Python (programming language)|Python]]
}}

'''ABC''' is an [[Imperative programming|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]].<ref>{{cite journal |title=An Alternative Simple Language and Environment for PCs |first1=Steven |last1=Pemberton |author1-link=Steven Pemberton |date=January 1987 |journal=IEEE Software |volume=4 |issue=1 |pages=56–64 |doi=10.1109/MS.1987.229797|s2cid=12788361 }}</ref> It is interactive, structured, [[High-level programming language|high-level]], and intended to be used instead of [[BASIC]], [[Pascal (programming language)|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 (programming language)|Python]], developed by [[Guido van Rossum]], who formerly worked for several years on the ABC system in the mid-1980s.<ref>{{cite magazine |last=Hamilton |first=Naomi |date=2008-05-08 |url=http://www.computerworld.com.au/index.php/id;66665771 |title=The A-Z of Programming Languages: Python |magazine=Computerworld |publisher=IDG Communications |url-status=dead |archive-url=https://web.archive.org/web/20081229095320/http://www.computerworld.com.au/index.php/id%3B66665771 |archive-date=2008-12-29 |quote=... I figured I could design and implement a language 'almost, but not quite, entirely unlike' ABC, improving upon ABC's deficiencies, ... |access-date=2020-09-04}}</ref><ref>{{cite web |last=Stewart |first=Bruce |date=2002-06-04 |url=http://www.onlamp.com/pub/a/python/2002/06/04/guido.html |title=An Interview with Guido van Rossum |website=ONLamp.com |publisher=O’Reilly Media |url-status=dead |archive-url=https://web.archive.org/web/20130313095540/http://www.onlamp.com/pub/a/python/2002/06/04/guido.html |archive-date=2013-03-13 |quote=... in my head I had analyzed some of the reasons it had failed. |access-date=2020-09-04}}</ref>

==Features==
Its designers claim that ABC [[Computer program|programs]] are typically around a quarter the size of the equivalent [[Pascal (programming language)|Pascal]] or [[C (programming language)|C]] programs, and more readable.<ref>{{cite web |last=Pemberton |first=Steven |date=2012-02-22 |url=https://homepages.cwi.nl/~steven/abc/ |title=The ABC Programming Language: a short introduction |website=[[Centrum Wiskunde & Informatica]] (CWI) |place=Amsterdam |access-date=2020-09-04}}</ref> Key features include:

*Only five basic [[data type]]s
*No required variable declarations
*Explicit support for [[top-down programming]]
*Statement nesting is indicated by [[indent style|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 application|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 variable]]s (persistent), and multiple workspaces, and is available as an [[Interpreter (computer software)|interpreter]]–[[compiler]]. {{As of|2020}}, 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 <code>words</code> in a document:<ref>{{FOLDOC|ABC}}</ref>

 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 collection

== Implementations ==
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.

==References==
{{Reflist}}

== Further reading ==
* {{cite book | last=Geurts | first=Leo | last2=Meertens | first2=Lambert | last3=Pemberton | first3=Steven | title=ABC Programmer's Handbook | publisher=Prentice Hall | publication-place=New York | date=1990-01-01 | isbn=0-13-000027-2 | url=https://homepages.cwi.nl/~steven/abc/programmers/handbook.html}}

{{Authority control}}

{{DEFAULTSORT:Abc}}
[[Category:Computer science in the Netherlands]]
[[Category:Dutch inventions]]
[[Category:Educational programming languages]]
[[Category:Information technology in the Netherlands]]
[[Category:Persistent programming languages]]
[[Category:Procedural programming languages]]
[[Category:Programming languages created in the 1980s]]