Puzzles/Quine - J Wiki

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Scheme legend
References

Create J program script that prints itself, so that

it is not empty
the locked (3!:6) script file, after the original is deleted, will restore the original

Discussion

Suppose, the script is called q.ijs, in bash shell:

$ ./jconsole -js fc=:\!: "exit'q.ijl'fwrite~3 fc 6(ferase]fread)'q.ijs'[load'files'"
$ ls q.*
q.ijl

$ ./jconsole q.ijl > q.ijs
$ ./jconsole q.ijs > q.out
$ ./jconsole -js "exit echo-:/fread&.>'q.ijs';'q.out'[load'files'"
1

in NT console

>jconsole -js "exit'q.ijl'fwrite~3!:6(ferase]fread)'q.ijs'[load'files'"
>dir /b q.*
q.ijl

>jconsole q.ijl > q.ijs
>jconsole q.ijs > q.out
>jconsole -js "exit echo-:/fread&.>'q.ijs';'q.out'[load'files'"
1

History

Original quine problem appeared 1 May, 2002 in JForum by DanBron.

The purpose of this puzzle is to stimulate more complex solutions.

Spoiler Alert!

Solutions

Please submit your solutions here.

No.	Scheme	Author	Date	Source	Quine/Notes
0	DMS-N	DanBron	2005-Nov-07	#N/A#	`0`
0	DMS-N	DanBron	2005-Nov-07	#N/A#	Technically, the shortest J program that prints itself.
1	DMS-V	DanBron	2005-Nov-07	#N/A#	`hello world`
1	DMS-V	DanBron	2005-Nov-07	#N/A#	This assumes that J has been reconfigured to use linear display form.
2	VCV-X	Josh ? <josh at cs.rutgers.edu>	1999-Oct-02 (mod. date of url)	The quine page	`".a=.'''".a=.'',q,q,~a#~1+a=q=.39{a.'`
2	VCV-X	Josh ? <josh at cs.rutgers.edu>	1999-Oct-02 (mod. date of url)	The quine page	This is the earliest example of a J quine I could find. ... and the only I've seen so far with odd number of characters -- -- AndrewNikitin 2005-12-18 04:30:02 ... J Quines with odd numbers of characters can be generated at will (e.g., the solution 30 and many of its potential variants) -- PepeQuintana 2012-05-25 00:19:34
3	VCV-T	PepeQuintana	2001-Feb-02	JForum message	`(],((39{a.)"_),],((39{a.)"_))'(],((39{a.)"_),],((39{a.)"_))'`
4	VCV-T	DanBron	2004-Jan-14	#N/A#	`(,(39{a.)&(,,[))'(,(39{a.)&(,,[))'`
5	VCV-T	EwartShaw	2005-Nov-07	this page	`(,],{:,{:)'(,],{:,{:)'''`
6	PMF-F	NollaigMacKenzie	2002-May-01	#N/A#	`(".'1!:1 <''foofile''') 1!:2 (2)`
6	PMF-F	NollaigMacKenzie	2002-May-01	#N/A#	This particular quine only works when it is stored in a script called 'foofile' (and executed therefrom).
7	PMF-A	DanBron	2004-Jan-14	#N/A#	`2 (1!:2)~ 1!:1 (3 : '(4!:3''''){~4!:4<''y.''' '')`
8	VCV-T	AndrewNikitin	2002-11-26	#N/A#	`(,{:)^:2,~'(,{:)^:2,~'''`
9	VCV-T	AndrewNikitin	2002-11-26	#N/A#	`(,{:,{:),~'(,{:,{:),~'''`
10	VCV-T	AndrewNikitin	2002-11-26	#N/A#	`(,,~@{:),~'(,,~@{:),~'''`
11	VCV-T	AndrewNikitin	2002-11-26	#N/A#	`(,~,{:,{:)'(,~,{:,{:)'''`
12	VCV	BJonas	2006-05-09	#N/A#	`(a,5!:5<'a')[a=:'(a,5!:5<''a'')[a=:'`
13	VCV	BJonas	2006-05-09	#N/A#	`(a=:'(a=:'"_ , 5!:5@<@('a'"_) , ')0'"_)0`
14	VCV	BJonas	2006-05-09	#N/A#	`(a=:3 : '''(a=:'',(5!:5<''a''),'')0''')0`
15	VCV	BJonas	2006-05-09	#N/A#	`(,,&')')0 :0` `(,,&')')0 :0` `)`
16	SPI	BJonas	2006-05-09	#N/A#	`exit stdout(,,&')')0 :0` `exit stdout(,,&')')0 :0` `)` (remove final newline)
17	SPI	BJonas	2006-05-09	#N/A#	`exit stdout(,,&(41 10{a.))0 :0` `exit stdout(,,&(41 10{a.))0 :0` `)`
18	VCV	BJonas	2006-05-09	#N/A#	`".a=:'''".a=:'',5!:5<''a'''`
19	VCV	BJonas	2006-05-09	#N/A#	`".a=:'''".a=:'''''','''''''',~(#~>:@=&'''''''')a'`
20	VCV	BJonas	2006-05-09	#N/A#	`3 :'3 :y.y.' '''3 :''''3 :y.y.'''' '''''','''''''',~(#~>:@=&'''''''')y.'`
21	VCV	BJonas	2006-05-09	#N/A#	`3 : '''3 :'',,~'' '''''','''''''',~(#~>:@=&'''''''')y.' '''3 :'',,~'' '''''','''''''',~(#~>:@=&'''''''')y.'`
22	VCV	BJonas	2006-05-09	#N/A#	`(,''''&,@:,&''''@:(#~>:@=&''''))'(,''''''''&,@:,&''''''''@:(#~>:@=&''''''''))'`
23	SPI	BJonas	2006-05-09	#N/A#	`exit stdout(,''''&,@:,&''''@:(#~>:@=&''''))'exit stdout(,''''''''&,@:,&''''''''@:(#~>:@=&''''''''))'` (remove trailing newline)
24	SPI	BJonas	2006-05-09	#N/A#	`exit stdout 3 :'3 :y.y.' '''exit stdout 3 :''''3 :y.y.'''' '''''','''''''',~(#~>:@=&'''''''')y.'` (remove trailing newline)
25	SPI	BJonas	2006-05-09	#N/A#	`exit stdout".a=:'''exit stdout".a=:'',5!:5<''a'''` (remove trailing newline)
26	VCV-T	PepeQuintana	2007-05-25	JForum message	`(,~,2#{:)'(,~,2#{:)'''`
27	VCV-T	PepeQuintana	2007-06-01	this page	`(,2#{:),~'(,2#{:),~'''`
28	VCV?-T	PepeQuintana	2007-05-28	JForum message	`({&a.,":)40 123 38 97 46 44 34 58 41` `Quote-less expression`
29	SPI/VCV?-T	PepeQuintana	2007-06-01	this page	`(1!:2)&2@({&a.,":)40 49 33 58 50 41 38 50 64 40 123 38 97 46 44 34 58 41` `A "true" Quine script derived from ({a.,":)40 123 38 97 46 44 34 58 41`
30	VCV?-T	PepeQuintana	2007-06-01	this page	`38 40 40 34 58 44 123 38 97 46 41 64 91 44 34 58 64 93 41&((":,{&a.)@[,":@])0j1` `A variable argument expression`
31	VCV-T	PepeQuintana	2007-06-01	this page	`'''&((2#{.@[),[,[,":@])'&((2#{.@[),[,[,":@])1.41421` `Another variable argument expression`
32	VCV?-T	PepeQuintana	2007-06-03	this page	`".'((34 46 39{]),{,":@[,39{])&a.40 40 51 52 32 52 54 32 51 57 123 93 41 44 123 44 34 58 64 91 44 51 57 123 93 41 38 97 46'` `A two-token expression`
33	VCV?-T	PepeQuintana	2007-08-27	this page	`(128!:2)~'a.&((40 49 50 56 33 58 50 41 126 39{[),],39{[)'` `A tacit self-applying counterpart`
34	VCV	BJonas	2008-09-25		`;@(2 0 0 0 0 1 0 1 0 1 0 2 0&{)'''';';';';@(2 0 0 0 0 1 0 1 0 1 0 2 0&{)'`
35	?	PepeQuintana	2009-05-07	this page	`'1 : (44 126 40 51 57 123 97 46 41 44 120{ a.)'1 : (44 126 40 51 57 123 97 46 41 44 120{ a.)` `An adverbial expression`
36	?	PepeQuintana	2009-05-07	this page	((([<@](<<'+');~':';[<@]((,'0');1);[<@](,'0');<)@])'a.&((40 40 40 91 60 64 93 40 60 60 39 43 39 41 59 126 39 58 39 59 91 60 64 93 40 40 44 39 48 39 41 59 49 41 59 91 60 64 93 40 44 39 48 39 41 59 60 41 64 93 41 39{[),{~,":@],39 41 53 33 58 48{[)97 46 38 40 40 52 48 32 52 48 32 52 48 32 57 49 32 54 48 32 54 52 32 57 51 32 52 48 32 54 48 32 54 48 32 51 57 32 52 51 32 51 57 32 52 49 32 53 57 32 49 50 54 32 51 57 32 53 56 32 51 57 32 53 57 32 57 49 32 54 48 32 54 52 32 57 51 32 52 48 32 52 48 32 52 52 32 51 57 32 52 56 32 51 57 32 52 49 32 53 57 32 52 57 32 52 49 32 53 57 32 57 49 32 54 48 32 54 52 32 57 51 32 52 48 32 52 52 32 51 57 32 52 56 32 51 57 32 52 49 32 53 57 32 54 48 32 52 49 32 54 52 32 57 51 32 52 49 32 51 57 123 91 41 44 123 126 44 34 58 64 93 44 51 57 32 52 49 32 53 51 32 51 51 32 53 56 32 52 56 123 91 41')5!:0 `An obfuscated adverbial expression`
37	VCV	BJonas	2009-05-12		`;2 0 0 0 0 1 0 1 0 1 0 2 0{'''';';';';2 0 0 0 0 1 0 1 0 1 0 2 0{'`
38	VCV	BJonas	2009-05-12		`;(1065345#:~13$3){'''';';';';(1065345#:~13$3){'`
39	VCV-T	PepeQuintana	2009-09-09	JForum message	`(],(''''"_ , (>:@:(''''"_ e.~ ]) # ]) , ''''"_) [ ('Whatever...'"_))'(],(''''''''"_ , (>:@:(''''''''"_ e.~ ]) # ]) , ''''''''"_) [ (''Whatever...''"_))'` `Quoting quotes withing quotes (see also the solution 22)`
40	?T	PepeQuintana	2009-09-09	this page	'''((("_)((<@:((,48{a.) ,&< ])) `(`((<@:((,48{a.) ,&< ])) 0)))) ((`:6) (((2#{.),,~)`) (`:6)))'((("_)((<@:((,48{a.) ,&< ])) `(`((<@:((,48{a.) ,&< ])) 0)))) ((`:6) (((2#{.),,~)`) (`:6))) `A tacit adverbial expression based on the solution 26`

Scheme legend

Scheme	Nick	Subclass	Description
Display matches specification	DMS		The idea for this quine is to create a line of input whose display, when executed, matches itself.
	Numeric	N	Most numeric constants in J display the same way they are specified
	Verb train	V	A analogous statement is true for verb trains. This fact, taken in conjunction with with the fact that an unassigned name is treated as a verb, allows lists of unassigned names (of certain lengths) to be DMS.
Verb cat verb in quotes	VCV		The idea for this quine is to create a function that produces its input concatenated with its input in single quotes. Since literal constants in J are specified by enclosing them in single quotes, the quine is effected by passing the function to itself as literal input.
	Tacit	T	The verb must be tacit
	Explicit	X	Same scheme, using immediate execution mode
Print my file	PMF		The idea for this quine is to create an script file that prints its own contents when loaded. This quine scheme only works when stored as a script (i.e. such will not work in J's immediate execution window). However, its nature allows us to make other quines of arbitrary length and complexity, because any script that executes these lines will print its entire contents.
	Fixed filename	F	The script must be stored with a specific filename, which filename is mentioned in the script.
	Arbitrary filename	A	The script can be stored with any filename, which it will discover for itself.
Script that Prints Itself	SPI		True solutions to this puzzle as stated. The constraint of locked files is only one way to require using itself and not the disk representation. Equivalent requirement would be to load into a noun, delete the file and execute the noun.

These are all good solutions, but to other great puzzles different from this one. E.g. puzzle for solutions using the DMS and VCV schemes could be formulated as "Find a J phrase for which (-: ".^:_) is true". -- OlegKobchenko 2005-11-07 19:12:08

Very good clasification by DanBron. PMF is also a different puzzle. The original problem still being sought is categorized as SPI -- OlegKobchenko 2005-11-08 20:54:41

Then again, SPI solutions can be derived from self-reproducing expressions (satisfying (-: ".)) as illustrated by the solution 29 -- PepeQuintana 2012-05-25 00:19:34

References

Ken Thompson, Reflections on Trusting Trust. Communication of the ACM, Vol. 27, No. 8, August 1984, pp. 761-763.