APL Wiki
APLs and related languages
The original APL\360 spawned many children: See: RetroAPL
While implementing sometimes quite different features, these all shared the distinctive APL character set. A recent addition to this group is Richard Smith's Rowan, an APL interpreter constructed from .Net assemblies.
Of these, APL2, SAX and VSAPL are in use primarily to maintain legacy systems. APL2000, APLX and Dyalog APL are in use for new systems development.
A+
In the 1980s, Arthur_Whitney designed an all-ASCII subset of APL for Morgan_Stanley, an investment bank. This language A+, became the principal platform for trading-room applications for about 15 years, and has since been published by Morgan Stanley.
J
From about 1990 Kenneth_E._Iverson worked with Roger_Hui and others on a successor to APL, abandoning the distinctive SpecialCharacters and naming all the primitives from the ASCII character set. This became known as the J_programming_language. It is used by an active community of largely solo programmers.
K
In the 1990s Arthur Whitney wrote the K_programming_language, a blend of APL and Lisp, as a proprietary successor to A+. Like J, it uses only ASCII characters. K is the basis of the KDB inverted-column database, and of the less-terse Q programming language.
Other languages
Other languages have made heavy borrowings from APL: MATLAB, Mathematica, the R_programming_language and the S_programming_language.
APL has exercised a strong influence on languages designed for functional_programming.
Other sources
Interview with Manfred von Thun, designer of Joy, in Vector
Why functional programming matters John Hughes, 1984