$ whois j

J

first released in 1990 · by Kenneth E. Iverson, Roger Hui

$ guessprog --inspect j

year: 1990
paradigm: array oriented
family: apl
memory: automatic gc
binding: dynamic
safety: strong

J(7)

AUTHORS: Kenneth E. Iverson, Roger Hui
HISTORY: J was developed in the early 1990s by Kenneth Iverson, the creator of APL, and Roger Hui, with input from Arthur Whitney. It is a successor to APL that keeps its array-oriented, terse style but uses only plain ASCII characters instead of APL's special keyboard symbols. J introduced tacit programming with forks and hooks, letting functions be composed without naming their arguments. Its source code was released under the GPL in 2011.
USAGE: J is a niche language with a small, enthusiastic community, used for data analysis, financial applications and mathematical exploration. Jsoftware maintains it along with the Jd columnar database.
SEE ALSO: J on Wikipedia ↗

$ cat examples.ijs

NB. Average as a fork: sum divided by count
avg =: +/ % #
avg 3 1 4 1 5 9 2 6

NB. Multiplication table of 1 to 5
*/~ 1 + i. 5

NB. The first 10 primes
p: i. 10

NB. Quicksort, recursing with $:
qs =: (($:@(<#[), (=#[), $:@(>#[)) ({~ ?@#)) ^: (1<#)
qs 3 1 4 1 5 9 2 6