Universal Turing machine: Difference between revisions

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The fixed tacit code was produced as follows:

<lang j> NB. Structured derivation of the universal Turing machine...

NB. Quick and dirty tacit toolkit...

o=. @:

c=."_

ver=. (0:`)([:^:)

d=. (fix=. (;:'f.')ver) (train=.(;:'`:')ver&6) (an=. <@:((,'0') (,&<) ]))

d=. (ver=. (an f. o fix'ver')ver o an f.)

z=. ((an'')`($ ,)`) (`:6)

d=. (a0=. `'') (a1=. (@:[) ((<'&')`) (`:6)) (a2=. (`(<(":0);_)) (`:6))

av=. ((an o fix'a0')`) (`(an o fix'a1')) (`(an o fix'a2') ) (`:6)

Fetch=. (ver o train ;:'&{::')&.> o i. f.av

tie=. ver o train ;:'`'

indices=. (, $~ 1 -.~ $) o (train"0 o ((1 -: L.)S:1 # <S:1) o (tie&'') o fix :: ] @:[)

f=. ((ver o train ;:'&{')) o indices o train f.av

'A B'=. 2 Fetch

head=. (;:'<@:') {.~ 2 * 1 = # o [

h=. train o (indices o train o (A f) (head , (B f) o ] , < o an o [ , (;:'}]')c) ]) f.av

DropIfNB=. < o ('('"_ , ] , ')'"_) o ((}: ^: ('NB.' -: 3&{. o > o {:)) &. ;:)

pipe=. ([ , ' o ' , ])&:>/ o |.

is=. ". o (, o ": o > , '=. ' , pipe o (DropIfNB;._2) o ". o ('0 ( : 0)'c)) f.av

NB.--------------------------------------------------------------------------------------

NB. Producing the main (dyadic) verb utm...

Note 0

NB. X (boxed list)...

Q - Instruction table

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C - Step Counter

)

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'Q S T P F B M PRINT MOVE C'=. 10 Fetch NB. 10 Boxes

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DisplayTape=. > o (((48 + ]) { a.c)@[ ; ((] $ ' 'c) , '^'c))

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'Q S T P F B M PRINT MOVE C'=. 10 Fetch NB. ~~10 verbs fetching the contents of~~ 10 Boxes

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display=. ((((": o (]&:>) o M) ,: (":@] C)) ,. ':'c ) ,. (T DisplayTape P))

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NB. Displaying state, symbol, tape / step and pointer

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DisplayTape=. > o (((48 + ]) { a.c)@[ ; ((] $ ' 'c) , '^'c))

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display=. ((((": o (]&:>) o M) ,: (":@] C)) ,. ':'c ) ,. (T DisplayTape P))

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amend=. 0 (0 {:: ])`(<@:(1 {:: ]))`(2 {:: ])} ]

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NB. Displaying state, symbol, tape / step and pointer

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NB. execute (monadic verb)...

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FillLeft=. (_1 = P ) {:: B NB. Expanding and filling the tape

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amend=. 0 (0 {:: ])`(<@:(1 {:: ]))`(2 {:: ])} ]

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FillRight=. ( P = # o T) {:: B NB. with 0's (if necessary)

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ia=. <@[ { ] NB. Selecting by the indices of an array

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NB. execute (monadic verb)...

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execute is

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FillLeft=. (_1 = P ) {:: B NB. Expanding and filling the tape

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FillRight=. ( P = # o T) {:: B NB. with 0's (if necessary)

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ia=. <@[ { ] NB. Selecting by the indices of an array

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execute is

T`(FillLeft , T , FillRight)h NB. Adjusting the tape

P`(P + _1 = P) h NB. and the pointer (if necessary)

M`(S ; P { T) h NB. Updating the state and reading the tape symbol

[ (smoutput o display)^:(0 = F | C) NB. Displaying intermediate cycles

(PRINT MOVE S)`(<"0 o (M ia Q))h NB. Performing the printing, moving and state actions

T`(amend o ((PRINT P T)f)) h NB. Printing symbol on tape at the pointer position

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)

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cc=. 'A changeless cycle was detected!'c

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halt=. _1 c = S NB. Halting when the current state is _1

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cc=. 'A changeless cycle was detected!'c

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rt=. ((({. , ({: % 3:) , 3:) o $) $ ,) o (}."1) o (". ;. _2)

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halt=. _1 c = S NB. Halting when the current state is _1

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NB. Reshaping the transition table as a 3D array (state,symbol,action)

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rt=. ((({. , ({: % 3:) , 3:) o $) $ ,) o (}."1) o (". ;. _2)

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NB. Reshaping the transition table as a 3D array (state,symbol,action)

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utm is NB. Universal Turing Machine (dyadic verb)

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utm is NB. Universal Turing Machine (dyadic verb)

,~ NB. Appending the arguments in reverse order

,&(;:5$',') NB. Appending 5 local boxes (B M PRINT MOVE C)

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display NB. Displaying (returning) the final status

)

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utm=. utm f. NB. Fixing the universal Turing machine code

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utm=. utm f. NB. Fixing the universal Turing machine code

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NB. The simulation code is produced by 77 (-@:[ ]\ 5!:5@<@:]) 'utm'</lang>

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NB. The simulation code is produced by 77 (-@:[ ]\ 5!:5@<@:]) 'utm'</lang>

=={{header|Java}}==