APL (programming language)
| Paradigm | array, functional, structured, modular |
|---|---|
| Designed by | Kenneth E. Iverson |
| Developer | Kenneth E. Iverson |
| First appeared | 1964 |
| Typing discipline | dynamic |
| Major implementations | |
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| Dialects | |
| Influenced by | |
| mathematical notation | |
| Influenced | |
APL (named after the book A Programming Language) is a programming language developed in the 1960s by Kenneth E. Iverson. Its central datatype is the multidimensional array. It uses a large range of special graphic symbols to represent most functions and operators, leading to very concise code. It has been an important influence on the development of concept modeling, spreadsheets, functional programming, and computer math packages. It has also inspired several other programming languages. It is still used today for certain applications.
The mathematical notation for manipulating arrays which developed into the APL programming language was developed by Iverson at Harvard University starting in 1957, and published in his A Programming Language in 1962. The preface states its premise:
Applied mathematics is largely concerned with the design and analysis of explicit procedures for calculating the exact or approximate values of various functions. Such explicit procedures are called algorithms or programs. Because an effective notation for the description of programs exhibits considerable syntactic structure, it is called a programming language.
In 1960, he began work for IBM and, working with Adin Falkoff, created APL based on the notation he had developed. This notation was used inside IBM for short research reports on computer systems, such as the Burroughs B5000 and its stack mechanism when stack machines versus register machines were being evaluated by IBM for upcoming computers.
Also in 1960, Iverson used his notation in a draft of the chapter "A Programming Language", written for a book he was writing with Fred Brooks, Automatic Data Processing, which would be published in 1963.
As early as 1962, the first attempt to use the notation to describe a complete computer system happened after Falkoff discussed with Dr. William C. Carter his work in the standardization of the instruction set for the machines that later became the IBM System/360 family.
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