The Associative Programming Language (APL) is a database language developed by General Motors Research Laboratories in 1966.[1]
APL was developed to provide high-level language data access and manipulation functions to support GM's CADANCE interactive computer graphics system. It was designed to integrate with PL/I.[2][3]
The underlying database is assumed to follow the network model. GM's first database manager was implemented via linked lists, but in 1977 the "Virtual Associative Access Manager" {VAAM) was developed to use virtual storage and implementing entity relationships as arrays.[1]: p.86 APL was later ported to the MCTS operating system.
Description
editAPL consists of six statements, CREATE, INSERT, FIND, FOR EACH, REMOVE, and DELETE,[1]: p.85 and miscellaneous functions such as counting the number of members in a set, determining the length or type of an entity, or locating an entity by name.[1]: p.95
- Create is a synonym for Allocate. It causes storage to be allocated for a based variable. A file or set where the data is to be allocated may be specified.
- Delete is a synonym for Free. Delete frees a based variable and optionally removes it from all sets of which it is a member.
- Find locates an entity that is a member of a set or container based on specified conditions. An optional
ELSEclause is executed if no entities are found. - For Each heads a group of statements to be executed for all entities or sets matching a specified condition.
- Insert inserts an entity into a specified set. Optionally, the placement of the new entity relative to other elements of the set may be specified.
- Let sets a locator variable to reference a specified set.
- Remove removes an entity from a set.
Implementation
editAPL statements were initially implemented as PL/I preprocessor macros, which translated into calls to the database manager. Later GM's Apple PL/I dialect supported APL directly in the language.
References
edit- ^ a b c d Price, Carol (1978), "APL/VAAM" (PDF), NASA Conference Publication 2055: Engineering and Scientific Data Management, NASA, pp. 85–97
- ^ Bachman, Charles (January 2006). "An interview with Charles W. Bachman". ACM Oral History interviews. doi:10.1145/1141880.1141882. ISBN 978-1-4503-1771-9. Retrieved June 29, 2024."George [Dodd] built a very attractive IDS like system, called 'Associative Programming Language' (APL)"
- ^ Dodd, George G. (November 1966). "APL: A language for associative data handling in PL/I". AFIPS '66 (Fall): Proceedings of the November 7-10, 1966, fall joint computer conference. pp. 677–684. doi:10.1145/1464291.146436 (inactive 11 July 2025). ISBN 978-1-4503-7893-2. Retrieved July 2, 2024.
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