A derivative and redesign of apl with added features and control structures. J is purely functional with lexical scope and more conventional control structures, plus several new concepts such as function rank and function arrays. J was designed and developed by Kennneth E. Iverson and Roger Hui <hui@yrloc.ipsa.reuter.com>. J uses only the ascii character set but has a spelling scheme that retains the advantages of apl's special alphabet. J is a conventional procedural programming language but can be used as a purely functional language.

Version 4.1 for ms-dos, Sun, Mac, Archimedes. Source available in C from iverson software, +1 (416) 925 6096.

Version 6 package from ISI includes an interpreter and tutorial. Ported to dec, next, sgi, sun-3, sun-4, vax, rs/6000, mips, macintosh, acorn archimedes, ibm pc, atari, 3b1, amiga.

J-mode gnu emacs macros available by .

["APL\?", Roger K.W. Hui et al, APL90 Conf Proc, Quote Quad 20(4):192-200].