ABC (programming language)
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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.[1] 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.[2][3]
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. Template:As of, 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 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
Further reading
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