K

K
Developer	Arthur Whitney
Released	1994
Latest release	K7 "Shakti" / 2019
Array model	Lists
Index origin	0
Function styles	dfn, tacit
Numeric types	ints, floats, extended precision floats, date, time, datetime
Unicode support	varies among implementations
File extensions	.k
Implementation language	C, B
Platforms	macOS, Linux, Windows, kOS
License	Free for personal use / Proprietary commercial software (free open source implementations exist)
Website	Kx Systems, Shakti
Download	K4, K7
Documentation	K4 K7
Influenced by	A+, J, Scheme
Influenced	Q, RAD

K denotes a family of programming languages designed by Arthur Whitney and commercialized by Morgan Stanley, Kx Systems, and Shakti. In 1985, while at Morgan Stanly, Whitney created the statically typed A dialect of APL. His colleagues extended A into A+ in 1988. Finally, Whitney presented the first K implementation in 1992, a "reduced instruction set" dialect which only used ASCII glyphs and limited arrays to (nested) vectors. For a long time, K's main role was as implementation language for Q, the query language of kdb+, which is an in-memory, column-based database. K7 ("Shakti K") is the first K to have full Unicode support, and it also uses a limited set non-ASCII symbols in the core language, for example Ø and ∞.