J (programming language)

J

Paradigm	Array, functional, function-level, tacit
Designed by	Kenneth E. Iverson, Roger Hui
Developer	JSoftware
First appeared	1990
Stable release	J804 / 4.012016
Typing discipline	dynamic
License	GPLv3
Filename extensions	.ijs
Website	jsoftware.com
Influenced by
APL, FP, FL
Influenced
K, NumPy

J - vector functional programming language. It is dialect APL. Unlike APL does not require a special keyboard to enter mathematical symbols, because it uses ASCII characters. The programming language J was developed in the early 1990s by Kenneth Iverson and Roger Hui (Roger Hui) (Eng.), As a synthesis of the APL (also developed by Iverson) and combinatorial programming languages FP and the FL , developed by Backus. Its main features - a focus on the MIMD instruction, the functional approach.

Data types

J supports three simple types:

• Numeric
• Literal (Character)
• Boxed

Vocabulary

Constantes
Controles
Foreigns
Partes de un programa

= Self-Classify • Equal	=. Is (Local)	=: Is (Global)
< Box • Less Than	<. Floor • Lesser Of (Min)	<: Decrement • Less Or Equal
> Open • Larger Than	>. Ceiling • Larger of (Max)	>: Increment • Larger Or Equal
_ Negative Sign / Infinity	_. Indeterminate	_: Infinity
 
+ Conjugate • Plus	+. Real / Imaginary • GCD (Or)	+: Double • Not-Or
* Signum • Times	*. Length/Angle • LCM (And)	*: Square • Not-And
- Negate • Minus	-. Not • Less	-: Halve • Match
% Reciprocal • Divide	%. Matrix Inverse • Matrix Divide	%: Square Root • Root
 
^ Exponential • Power	^. Natural Log • Logarithm	^: Power
$ Shape Of • Shape	$. Sparse	$: Self-Reference
~ Reflex • Passive / EVOKE	~. Nub •	~: Nub Sieve • Not-Equal
| Magnitude • Residue	|. Reverse • Rotate (Shift)	|: Transpose
 
. Determinant • Dot Product	.. Even	.: Odd
: Explicit / Monad-Dyad	:. Obverse	:: Adverse
, Ravel • Append	,. Ravel Items • Stitch	,: Itemize • Laminate
; Raze • Link	;. Cut	;: Word Formation •
 
# Tally • Copy	#. Base 2 • Base	#: Antibase 2 • Antibase
! Factorial • Out Of	!. Fit (Customize)	!: Foreign
/ Insert • Table	/. Oblique • Key	/: Grade Up • Sort
\ Prefix • Infix	\. Suffix • Outfix	\: Grade Down • Sort
 
[ Same • Left	 	[: Cap
] Same • Right	 	 
{ Catalogue • From	{. Head • Take	{: Tail •   {:: Map • Fetch
} Item Amend • Amend	}. Behead • Drop	}: Curtail •
 
" Rank	". Do • Numbers	": Default Format • Format
` Tie (Gerund)	 	`: Evoke Gerund
@ Atop	@. Agenda	@: At
& Bond / Compose	&. Under (Dual)	&: Appose
	&.: Under
? Roll • Deal	?. Roll • Deal (fixed seed)
 
a. Alphabet	a: Ace (Boxed Empty)	A. Anagram Index • Anagram
b. Boolean / Basic	c. Characteristic Values	C. Cycle-Direct • Permute
d. Derivative	D. Derivative	D: Secant Slope
e. Raze In • Member (In)	E. • Member of Interval	f. Fix
 
H. Hypergeometric	i. Integers • Index Of	i: Integers • Index Of Last
j. Imaginary • Complex	L. Level Of	L: Level At
m. n. Explicit Noun Args	NB. Comment	o. Pi Times • Circle Function
p. Polynomial	p.. Poly. Deriv. • Poly. Integral	p: Primes •
 
q: Prime Factors • Prime Exponents	r. Angle • Polar	s: Symbol
S: Spread	t. Taylor Coefficient	t: Weighted Taylor
T. Taylor Approximation	u. v. Explicit Verb Args	u: Unicode
x. y. Explicit Arguments	x: Extended Precision	_9: to 9: Constant Functions

Examples

An example of "Hello, world!" Program

#!/bin/jc
   echo 'Hello, world!'
   exit ''

Some examples of use avg:

  v=: ?. 20 $100     NB. a random vector
  v
46 55 79 52 54 39 60 57 60 94 46 78 13 18 51 92 78 60 90 62
  avg v
59.2

  4 avg\ v            NB. moving average on periods of size 4
58 60 56 51.25 52.5 54 67.75 64.25 69.5 57.75 38.75 40 43.5 59.75 70.25 80 72.5

  m=: ?. 4 5 $50     NB. a random matrix
  m
46  5 29  2  4
39 10  7 10 44
46 28 13 18  1
42 28 10 40 12

The implementation of quicksort:

  sel=: adverb def 'u # ['   quicksort=: verb define
    if. 1 >: #y do. y
    else.
     (quicksort y <sel e),(y =sel e),quicksort y >sel e=.y{~?#y
    end.
   )

Control structures

J provides control structures, similar to other procedural languages. For example:

*assert.
*break.
*continue.
*for.
*goto_label.
*if. else. elseif.
*return.
*select. case.
*throw.
*try. catch.
*while. whilst.

External links

1. Description
2. Official website
3. help
4. Ewart Shaw