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{{Infobox array language
{{Infobox array language
| logo                  = [[File:Jblue.png]]
| file ext              = .ijs
| file ext              = .ijs
| array model            = [[Flat array model|flat]] with [[Box|boxes]]
| array model            = [[Flat array model|flat]] with [[Box|boxes]]
| index origin          = 0
| index origin          = 0
| function styles        = explicit, [[tacit]]
| function styles        = [[Anonymous function|explicit]], [[tacit]]
| numeric types          = 64-bit integer, complex float, [[extended integer]], [[rational]]
| numeric types          = 64-bit integer, [[complex]] float, [[extended integer]], [[rational]]
| unicode support        = full; distinct byte and code point types
| unicode support        = full; distinct byte and code point types
| released              = 1990
| released              = 1990
| developer              = [[JSoftware]] ([[Kenneth E. Iverson]], [[Roger Hui]])
| developer              = [[Jsoftware]] ([[Ken Iverson]], [[Roger Hui]])
| latest release version = J807 / 2018-10-08
| latest release version = j903 / 2021-12-17
| influenced by          = [[SHARP APL]], [[Rationalized APL]], [https://en.wikipedia.org/wiki/FP_(programming_language) FP], [https://en.wikipedia.org/wiki/FL_(programming_language) FL]
| influenced by          = [[SAX]], [[Rationalized APL]]
| influenced            = [[Dyalog APL]], [[I]]
| influenced            = [[Dyalog APL]], [[NARS2000]], [[I]], [[BQN]]
| implementation language= [https://en.wikipedia.org/wiki/C_(programming_language) C]
| implementation language= [[wikipedia:C (programming language)|C]]
| source                = [https://github.com/jsoftware/jsource GitHub]
| platforms              = x86, x86_64
| platforms              = x86, x86_64
| operating systems      = Windows, Linux, macOS
| operating systems      = Windows, Linux, macOS
| license                = [https://en.wikipedia.org/wiki/GNU_General_Public_License GPLv3]
| license                = [[wikipedia:GNU General Public License|GPLv3]]
| website                = [https://www.jsoftware.com/ www.jsoftware.com]
| website                = [https://www.jsoftware.com/ www.jsoftware.com]
| forum                  = [https://code.jsoftware.com/wiki/System/Forums multiple]
| download              = [https://code.jsoftware.com/wiki/System/Installation System/Installation]
| download              = [https://code.jsoftware.com/wiki/System/Installation System/Installation]
| documentation          = [https://www.jsoftware.com/help/dictionary/contents.htm Dictionary], [https://code.jsoftware.com/wiki/NuVoc NuVoc]
| documentation          = [https://www.jsoftware.com/help/dictionary/contents.htm Dictionary], [https://code.jsoftware.com/wiki/NuVoc NuVoc]
| run online            = [https://joebo.github.io/j-emscripten/ Emscripten], [https://jsoftware.github.io/j-playground/bin/html/ J playground]
}}
}}
'''J''' is an array language loosely following the [[SHARP APL]] tradition which uses [[wikipedia:ASCII|ASCII]] characters for primitive functionality and builds in [[leading axis theory]] and [[tacit programming]] as foundational design principles. J discards backwards compatibility with older APLs in order to simplify and regularize its syntax, redesign primitives to work on leading axes, and disentangle [[reduction]] from [[scan]]s and [[windowed reduction]]s (yielding the [[Prefix operator|prefix]] and [[infix operator]]s). However, J concepts such as [[function train]]s and the [[Indices]] function have been adopted by later APLs such as [[NARS2000]], [[Dyalog APL]], and [[dzaima/APL]]. J breaks the APL convention of writing primitives with a single glyph: instead, they are spelled with a single ASCII character possibly followed by one or two periods (<source lang=j inline>.</source>) or colons (<source lang=j inline>:</source>). It is also notable for its use of terms from English grammar to describe the language. For example, [[function]]s are called "verbs" while arrays are called "nouns".


The '''J''' programming language combines an ASCII encoding of APL as embodied by [[SHARP APL]] with functional techniques developed by [https://en.wikipedia.org/wiki/John_Backus John Backus] for the [https://en.wikipedia.org/wiki/FP_(programming_language) FP] and [https://en.wikipedia.org/wiki/FL_(programming_language) FL] languages. J is characterized by its use of [[leading axis theory]] as a foundational design principle and its [[tacit programming]] capabilities. [[Function trains]] are a key J feature and were later adopted by [[Dyalog APL]]. J's primitives consist of a single ASCII character possibly followed by one or two periods (<source lang=j inline>.</source>) or colons (<source lang=j inline>:</source>). It is also notable for its use of terms from English grammar to describe the language. For example, [[functions]] are called "verbs" while arrays are called "nouns".
== History ==


{{APL programming language}}
J was initially designed primarily by [[Ken Iverson]] and [[Roger Hui]], with input from [[Arthur Whitney]] and [[Eric Iverson]]. Ken had been considering a new language based on [[A Dictionary of APL]] but without the backwards compatibility constraints of APL and the custom character set (which was a major technical issue at the time). In "A Personal View of APL"<ref name="personal">[[Ken Iverson|Iverson, K.E.]] [https://www.jsoftware.com/papers/APLPersonalView.htm "A Personal View of APL"]. IBM Systems Journal, Volume 30, Number 4. 1991-12.</ref> he gives the following as the most important goals for a new language:
{{quote|
* Is available as “shareware”, and is inexpensive enough to be acquired by students as well as by schools
* Can be printed on standard printers
* Runs on a wide variety of computers
* Provides the simplicity and the generality of the latest thinking in APL}}
 
Iverson's phrase "the latest thinking in APL" refers to two major breakthroughs made that decade: the invention of the [[Rank operator]] by [[Arthur Whitney]] in 1982 and subsequent development of [[leading axis theory]], and the invention of [[function train]]s by Iverson and [[Eugene McDonnell]] in 1988.
 
In the summer of 1989 Whitney visited Iverson, who discussed with Whitney his plans for a new array language. Whitney wrote a one-page prototype for the language in a single afternoon using [[wikipedia:C (programming language)|C]]. Iverson shared the program with [[Roger Hui]], who began working on J on August 27 and quickly produced a more complete prototype.<ref name="personal"/><ref>[[Roger Hui|Hui, Roger]]. [https://code.jsoftware.com/wiki/Essays/Incunabulum "Incunabulum"]. From ''An Implementation of J'', Appendix A: Incunabulum, 1992-01-27.</ref><ref name>McIntyre, Donald. [https://web.archive.org/web/20060410225556/http://elliscave.com/APL_J/rogerhui.htm "A Tribute to Roger Hui, presented at APL96"]. 1996.</ref> The name "J", chosen by Hui when saving the first source code file, is meaningless: in ''An Implementation of J'', Hui remarks "Why 'J'? It is easy to type."<ref>[[Roger Hui|Hui, Roger]]. [https://sblom.github.io/openj-core/ioj.htm ''An Implementation of J''] ([http://www.jsoftware.com/books/pdf/aioj.pdf pdf]), Preface. 1992-01-27.</ref> J was first presented by Hui and Iverson, including a live demo, at a meeting of the Toronto APLSIG in February 1990.<ref name="remembering">[[Roger Hui|Hui, Roger]]. [http://keiapl.org/rhui/remember.htm "Remembering Ken Iverson"]. 2004-11.</ref>
 
In 1990 Hui and Iverson joined Iverson Software Inc. (now [[Jsoftware]]), which had been founded that year by [[Eric Iverson]] to sell a [[SHARP APL]] product. Eric converted his SHARP [[session]] to use with J as Hui continued on the core language's implementation. The J language, including Eric's session environment, was first released at [[APL90]] in Copenhagen August 1990.<ref name="remembering"/>
 
== Versions ==
 
J has used two numbering systems. Releases prior to 1994 used a single decimal and the naming scheme "Version X.Y", while those after used two decimals and are called "Release X.YY", or "JXYY" as in "J807".
 
{|class=wikitable
! Version !! Date    !! Features
|-
| 2.0  || 1990-08-09 || (APL90)
|-
| 2.7  || 1990-10-22 || [[Rank operator|Rank]] with a function right operand, [[Under]]
|-
| 2.8  || 1990-11-15 ||
|-
| 2.9  || 1991-02-15 || Monadic <source lang=j inline>+:</source> (double), <source lang=j inline>-:</source> (halve), <source lang=j inline>*:</source> (square), dyadic <source lang=j inline>":</source> ([[Format]]), constant functions <source lang=j inline>0:</source> and <source lang=j inline>1:</source>
|-
| 3.0  || 1991-03-17 || Changes to spellings, [[Reverse]] with [[Variant]] to specify [[fill]]
|-
| 3.1  || 1991-05-17 || [[Determinant]] (<source lang=j inline>.</source>)
|-
| 3.2  || 1991-06-02 || <source lang=j inline>,.</source> for ravel items (like [[Table]]) and append lists, <source lang=j inline>;</source> for [[Raze]] and [[Link]], <source lang=j inline>@.</source> for agenda, non-[[close composition]]s
|-
| 3.3  || 1991-06-25 || Dyadic <source lang=j inline>,.</source> changed to append items, more types of trains
|-
| 3.4  || 1991-07-15 || <source lang=j inline>NB.</source> for comments
|-
| 4.0  || 1991-11-23 || Monadic <source lang=j inline>+.</source> and <source lang=j inline>*.</source> for complex components and phase/magnitude with <source lang=j inline>j.</source> and <source lang=j inline>r.</source> to recombine, <source lang=j inline>^:_</source> for power limit
|-
| 4.1  || 1992-02-02 || <source lang=j inline>^!.p</source> for rising/falling factorials
|-
| 4.2  || 1992-03-19 ||
|-
| 5.0  || 1992-06-22 || [[Variant]] to specify [[comparison tolerance]] and [[fill]] for [[Take]]
|-
| 5.1  || 1992-07-28 || <source lang=j inline>f.</source> to expand a tacit function containing names, constant functions <source lang=j inline>2:</source> to <source lang=j inline>9:</source>
|-
| 5.1a || 1992-08-11 ||
|-
| 6.0  || 1992-10-24 || Error handling with <source lang=j inline>::</source>, additional [[system function]]s
|-
| 6.1  || 1992-11-26 || [[Amend]] operator <source lang=j inline>}</source>
|-
| 6.2  || 1992-12-20 || Derivative operator <source lang=j inline>D.</source>
|-
| 7.0  || 1993-11-14 || [[wikipedia:Taylor series|Taylor series]] operators <source lang=j inline>t.</source> and <source lang=j inline>T.</source>
|}
 
{|class=wikitable
! Release !! Date    !! Features
|-
| 2.01 || 1994-09-01 || [[Control structure]]s, many additional [[system function]]s
|-
| 2.03 || 1994-09-21 ||
|-
| 2.04 || 1994-11-28 ||
|-
| 2.05 || 1995-02-26 || Additional [[inverse]]s, [[primitive array]] <source lang=j inline>a:</source> ("ace")
|-
| 2.06 || 1995-05-30 || More [[inverse]]s, hypergeometric operator <source lang=j inline>H.</source>, and prime functions <source lang=j inline>p.</source>, <source lang=j inline>p:</source>, and <source lang=j inline>q:</source>
|-
| 3.01 || 1996-01-16 || Repeatable [[Roll]]/[[Deal]] <source lang=j inline>?.</source>, [[Depth]] <source lang=j inline>L.</source> and [[Depth operator]] <source lang=j inline>L:</source>, [[total array ordering]]
|-
| 3.02 || 1996-06-24 || [[Pick]] variant <source lang=j inline>{::</source>, [[extended precision]] types
|-
| 3.03 || 1996-12-13 || [[Multiple assignment]] using a string target
|-
| 3.04 || 1997-05-19 || More operators with gerund operands, <source lang=j inline>for.</source> and <source lang=j inline>select.</source> [[control structure]]s
|-
| 3.05 || 1997-09-27 || Extended dyad <source lang=j inline>q:</source> ([[Factor]]) to take a negative left argument
|-
| 4.01 || 1998-03-22 || [[Find]] (<source lang=j inline>E.</source>) and [[Index of Last]] (<source lang=j inline>i:</source>)
|-
| 4.02 || 1998-11-07 || Symmetric range monad (<source lang=j inline>i:</source>), infinite left arguments to [[Take]]
|-
| 4.03 || 1999-04-21 ||
|-
| 4.04 || 2000-01-02 || [[Sparse array]] support
|-
| 4.05 || 2000-09-05 || [[Comparison tolerance]] for [[Key]]
|-
| 4.06 || 2001-05-09 || <source lang=j inline>assert.</source> and <source lang=j inline>throw.</source>, Symbols (<source lang=j inline>s:</source>) and Unicode (<source lang=j inline>u:</source>), multiple axes in [[Cut]] operator
|-
| 5.01 || 2002-09-10 || Non-[[Close composition|close]] [[Under]] <source lang=j inline>&.:</source>, Bitwise Operations (<source lang=j inline>b.</source>), Polynomial Derivative (<source lang=j inline>p..</source>), Head (<source lang=j inline>{.</source>) and Tail (<source lang=j inline>{:</source>) allow [[empty]] arguments
|-
| 5.02 || 2003-05-21 ||
|-
| 5.03 || 2004-03-19 || [[Indices]] (<source lang=j inline>I.</source>), Sequential Machine (<source lang=j inline>;:</source>)
|-
| 5.04 || 2005-03-18 || J64 (64-bit version) introduced, boxed right argument for [[Power operator]], [[scalar extension]] for left argument of [[Cut]] (<source lang=j inline>;.</source>)
|-
| 6.01 || 2006-07-21 || Noun left arguments in trains (<source lang=j inline>N0 V1 V2</source>), dots removed from explicit argument names (<source lang=j inline>y.</source> to <source lang=j inline>y</source>, etc.), [[Interval Index]] (<source lang=j inline>I.</source>)
|-
| 6.02 || 2008-02-29 || [[Index Of]] (<source lang=j inline>i.</source>) extended to allow unmatched cell shapes, Memoize adverb (<source lang=j inline>M.</source>)
|-
| 7.01 || 2010-08-05 || GTK IDE
|-
| 7.02 ||            ||
|-
| 8.01 || 2014-02    || Qt IDE
|-
| 8.02 || 2014-08-02 || Qt IDE improved
|-
| 8.03 || 2014-12-09 || Native read/write of jpeg and png images
|-
| 8.04 || 2016-01-04 ||
|-
| 8.05 || 2016-12-19 || Improved UTF-8 handling, memory allocator rewritten with more in-place argument usage
|-
| 8.06 || 2017-11-12 || Allow array right operands to [[Atop]] and Adverse (<source lang=j inline>::</source>), treating as constant functions, improved [[Vector instructions|vector instruction]] usage
|-
| 8.07 || 2018-10-08 || Removed support for dot-style explicit arguments (e.g. <source lang=j inline>y.</source>)
|-
| 9.01 || 2019-12-15 || Iteration primitives <source lang=j inline>F..</source>, <source lang=j inline>F.:</source>, <source lang=j inline>F.</source>, <source lang=j inline>F:.</source>, <source lang=j inline>F::</source>, <source lang=j inline>F:</source>; Remove calculus operators <source lang=j inline>d.</source>, <source lang=j inline>D.</source>, <source lang=j inline>D:</source>, <source lang=j inline>t.</source>, <source lang=j inline>t:</source>, <source lang=j inline>T.</source>, <source lang=j inline>..</source>, <source lang=j inline>.:</source>; <source lang=j inline>gerund"r</source>
|-
| 9.02 || 2020-12-13 || "Direct definition" syntax for explicit functions, special semidual form <source lang=j inline>u&.:(a:`v)</source> added, minor incompatible changes
|-
| 9.03 || 2021-12-17 || Modifier trains and other combinations, foreigns to enable nameref caching, Kahan summation with <source lang=j inline>+/!.0</source>
|}
 
== References ==
 
<references />
{{APL dialects}}[[Category:Array languages]][[Category:Flat array languages]][[Category:Leading axis languages]][[Category:Languages with tacit programming]][[Category:ASCII languages]]

Revision as of 21:25, 21 June 2022

J is an array language loosely following the SHARP APL tradition which uses ASCII characters for primitive functionality and builds in leading axis theory and tacit programming as foundational design principles. J discards backwards compatibility with older APLs in order to simplify and regularize its syntax, redesign primitives to work on leading axes, and disentangle reduction from scans and windowed reductions (yielding the prefix and infix operators). However, J concepts such as function trains and the Indices function have been adopted by later APLs such as NARS2000, Dyalog APL, and dzaima/APL. J breaks the APL convention of writing primitives with a single glyph: instead, they are spelled with a single ASCII character possibly followed by one or two periods (.) or colons (:). It is also notable for its use of terms from English grammar to describe the language. For example, functions are called "verbs" while arrays are called "nouns".

History

J was initially designed primarily by Ken Iverson and Roger Hui, with input from Arthur Whitney and Eric Iverson. Ken had been considering a new language based on A Dictionary of APL but without the backwards compatibility constraints of APL and the custom character set (which was a major technical issue at the time). In "A Personal View of APL"[1] he gives the following as the most important goals for a new language:

  • Is available as “shareware”, and is inexpensive enough to be acquired by students as well as by schools
  • Can be printed on standard printers
  • Runs on a wide variety of computers
  • Provides the simplicity and the generality of the latest thinking in APL

Iverson's phrase "the latest thinking in APL" refers to two major breakthroughs made that decade: the invention of the Rank operator by Arthur Whitney in 1982 and subsequent development of leading axis theory, and the invention of function trains by Iverson and Eugene McDonnell in 1988.

In the summer of 1989 Whitney visited Iverson, who discussed with Whitney his plans for a new array language. Whitney wrote a one-page prototype for the language in a single afternoon using C. Iverson shared the program with Roger Hui, who began working on J on August 27 and quickly produced a more complete prototype.[1][2][3] The name "J", chosen by Hui when saving the first source code file, is meaningless: in An Implementation of J, Hui remarks "Why 'J'? It is easy to type."[4] J was first presented by Hui and Iverson, including a live demo, at a meeting of the Toronto APLSIG in February 1990.[5]

In 1990 Hui and Iverson joined Iverson Software Inc. (now Jsoftware), which had been founded that year by Eric Iverson to sell a SHARP APL product. Eric converted his SHARP session to use with J as Hui continued on the core language's implementation. The J language, including Eric's session environment, was first released at APL90 in Copenhagen August 1990.[5]

Versions

J has used two numbering systems. Releases prior to 1994 used a single decimal and the naming scheme "Version X.Y", while those after used two decimals and are called "Release X.YY", or "JXYY" as in "J807".

Version Date Features
2.0 1990-08-09 (APL90)
2.7 1990-10-22 Rank with a function right operand, Under
2.8 1990-11-15
2.9 1991-02-15 Monadic +: (double), -: (halve), *: (square), dyadic ": (Format), constant functions 0: and 1:
3.0 1991-03-17 Changes to spellings, Reverse with Variant to specify fill
3.1 1991-05-17 Determinant (.)
3.2 1991-06-02 ,. for ravel items (like Table) and append lists, ; for Raze and Link, @. for agenda, non-close compositions
3.3 1991-06-25 Dyadic ,. changed to append items, more types of trains
3.4 1991-07-15 NB. for comments
4.0 1991-11-23 Monadic +. and *. for complex components and phase/magnitude with j. and r. to recombine, ^:_ for power limit
4.1 1992-02-02 ^!.p for rising/falling factorials
4.2 1992-03-19
5.0 1992-06-22 Variant to specify comparison tolerance and fill for Take
5.1 1992-07-28 f. to expand a tacit function containing names, constant functions 2: to 9:
5.1a 1992-08-11
6.0 1992-10-24 Error handling with ::, additional system functions
6.1 1992-11-26 Amend operator }
6.2 1992-12-20 Derivative operator D.
7.0 1993-11-14 Taylor series operators t. and T.
Release Date Features
2.01 1994-09-01 Control structures, many additional system functions
2.03 1994-09-21
2.04 1994-11-28
2.05 1995-02-26 Additional inverses, primitive array a: ("ace")
2.06 1995-05-30 More inverses, hypergeometric operator H., and prime functions p., p:, and q:
3.01 1996-01-16 Repeatable Roll/Deal ?., Depth L. and Depth operator L:, total array ordering
3.02 1996-06-24 Pick variant {::, extended precision types
3.03 1996-12-13 Multiple assignment using a string target
3.04 1997-05-19 More operators with gerund operands, for. and select. control structures
3.05 1997-09-27 Extended dyad q: (Factor) to take a negative left argument
4.01 1998-03-22 Find (E.) and Index of Last (i:)
4.02 1998-11-07 Symmetric range monad (i:), infinite left arguments to Take
4.03 1999-04-21
4.04 2000-01-02 Sparse array support
4.05 2000-09-05 Comparison tolerance for Key
4.06 2001-05-09 assert. and throw., Symbols (s:) and Unicode (u:), multiple axes in Cut operator
5.01 2002-09-10 Non-close Under &.:, Bitwise Operations (b.), Polynomial Derivative (p..), Head ({.) and Tail ({:) allow empty arguments
5.02 2003-05-21
5.03 2004-03-19 Indices (I.), Sequential Machine (;:)
5.04 2005-03-18 J64 (64-bit version) introduced, boxed right argument for Power operator, scalar extension for left argument of Cut (;.)
6.01 2006-07-21 Noun left arguments in trains (N0 V1 V2), dots removed from explicit argument names (y. to y, etc.), Interval Index (I.)
6.02 2008-02-29 Index Of (i.) extended to allow unmatched cell shapes, Memoize adverb (M.)
7.01 2010-08-05 GTK IDE
7.02
8.01 2014-02 Qt IDE
8.02 2014-08-02 Qt IDE improved
8.03 2014-12-09 Native read/write of jpeg and png images
8.04 2016-01-04
8.05 2016-12-19 Improved UTF-8 handling, memory allocator rewritten with more in-place argument usage
8.06 2017-11-12 Allow array right operands to Atop and Adverse (::), treating as constant functions, improved vector instruction usage
8.07 2018-10-08 Removed support for dot-style explicit arguments (e.g. y.)
9.01 2019-12-15 Iteration primitives F.., F.:, F., F:., F::, F:; Remove calculus operators d., D., D:, t., t:, T., .., .:; gerund"r
9.02 2020-12-13 "Direct definition" syntax for explicit functions, special semidual form u&.:(a:`v) added, minor incompatible changes
9.03 2021-12-17 Modifier trains and other combinations, foreigns to enable nameref caching, Kahan summation with +/!.0

References

  1. 1.0 1.1 Iverson, K.E. "A Personal View of APL". IBM Systems Journal, Volume 30, Number 4. 1991-12.
  2. Hui, Roger. "Incunabulum". From An Implementation of J, Appendix A: Incunabulum, 1992-01-27.
  3. McIntyre, Donald. "A Tribute to Roger Hui, presented at APL96". 1996.
  4. Hui, Roger. An Implementation of J (pdf), Preface. 1992-01-27.
  5. 5.0 5.1 Hui, Roger. "Remembering Ken Iverson". 2004-11.
APL dialects [edit]
Maintained APL+WinAPL2APL64APL\ivApletteAprilCo-dfnsDyalog APLdzaima/APLExtended Dyalog APLGNU APLKAPNARS2000Pometo
Historical A Programming LanguageA+ (A) ∙ APL#APL\360APL/700APL\1130APL\3000APL.68000APL*PLUSAPL.jlAPL.SVAPLXIverson notationIVSYS/7090NARSngn/aplopenAPLOperators and FunctionsPATRowanSAXSHARP APLRationalized APLVisualAPL (APLNext) ∙ VS APLYork APL
Derivatives AHPLBQNCoSyELIGleeIIvyJJellyJellyfishK (Q, KDB+) ∙ Lang5NialRAD
Overviews Timeline of array languagesTimeline of influential array languagesFamily tree of array languages