ABC (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. 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, the latest version is 1.05.02, and it is ported to Unix, DOS, Atari, and Apple MacOS.