Create a kind of quine, such that the program prints one character of itself, then two, then three and so on

Question

Create quine variant such that the program prints its first character, then the first two, then three and so on until the whole program is printed.

Example

Suppose your code is @@@@@2 in some language. Then the output should be

@
@@
@@@
@@@@
@@@@@
@@@@@2

in that order, each line separated by a newline.

The winner is the shortest quine like this.

Answer 1

Jelly, 10 bytes

“;⁾vṾÄY”vṾ

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How it works

“;⁾vṾÄY”vṾ  Main link. No arguments.

“;⁾vṾÄY”    Set the return value to the string ';⁾vṾÄY'.
         Ṿ  Uneval; yield a string representation of the string, i.e., '“;⁾vṾÄY”'.
        v   Dyadic eval; execute the string to the left, passing the string to the
            right as argument.
  ⁾vṾ         Literal; yield 'vṾ'.
 ;            Concatenate the argument ('“;⁾vṾÄY”') and 'vṾ', yielding '“;⁾vṾÄY”vṾ'.
     Ä        Accumulate; take the cumulative sum.
              Since string addition is concatenation in Python (and Jelly doesn't do
              type checks), this yields all prefixes of the string.
      Y       Join the prefixes, separated by linefeeds.

Answer 2

Husk, 18 bytes

G:""S+s"G:\"\"S+s"

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Explanation

An extension of the standard quine S+s"S+s". To get all the prefixes we cannot use ḣ (heads), because ḣS+s"ḣS+s" would show "ḣS+s" which results in "\7715S+s":

ḣS+s"ḣS+s"

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So we need to re-implement heads without using any unicode, this can be done by scanl snoc "" (snoc is just a flippped version of (:)), ie. G:"" which is ASCII.

Answer 3

Oracle SQL, 154 bytes

select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;

Test in SQL Plus

SQL> set lines 160 pages 0
SQL> select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;
s
se
sel
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select substr(rpad
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select substr(rpad(1,240,'||ch
select substr(rpad(1,240,'||chr
select substr(rpad(1,240,'||chr(
select substr(rpad(1,240,'||chr(3
select substr(rpad(1,240,'||chr(39
select substr(rpad(1,240,'||chr(39)
select substr(rpad(1,240,'||chr(39))
select substr(rpad(1,240,'||chr(39)),
select substr(rpad(1,240,'||chr(39)),5
select substr(rpad(1,240,'||chr(39)),53
select substr(rpad(1,240,'||chr(39)),53,
select substr(rpad(1,240,'||chr(39)),53,l
select substr(rpad(1,240,'||chr(39)),53,le
select substr(rpad(1,240,'||chr(39)),53,lev
select substr(rpad(1,240,'||chr(39)),53,leve
select substr(rpad(1,240,'||chr(39)),53,level
select substr(rpad(1,240,'||chr(39)),53,level)
select substr(rpad(1,240,'||chr(39)),53,level)f
select substr(rpad(1,240,'||chr(39)),53,level)fr
select substr(rpad(1,240,'||chr(39)),53,level)fro
select substr(rpad(1,240,'||chr(39)),53,level)from
select substr(rpad(1,240,'||chr(39)),53,level)from
select substr(rpad(1,240,'||chr(39)),53,level)from d
select substr(rpad(1,240,'||chr(39)),53,level)from du
select substr(rpad(1,240,'||chr(39)),53,level)from dua
select substr(rpad(1,240,'||chr(39)),53,level)from dual
select substr(rpad(1,240,'||chr(39)),53,level)from dual
select substr(rpad(1,240,'||chr(39)),53,level)from dual c
select substr(rpad(1,240,'||chr(39)),53,level)from dual co
select substr(rpad(1,240,'||chr(39)),53,level)from dual con
select substr(rpad(1,240,'||chr(39)),53,level)from dual conn
select substr(rpad(1,240,'||chr(39)),53,level)from dual conne
select substr(rpad(1,240,'||chr(39)),53,level)from dual connec
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect b
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by l
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by le
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by lev
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by leve
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<1
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<15
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;s
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;se
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;sel
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;sele
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;selec
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select s
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select su
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select sub
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select subs
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select subst
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(r
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rp
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpa
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,2
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,24
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,240
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,240,
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,240,'
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,240,'|
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,240,'||
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,240,'||c
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,240,'||ch
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,240,'||chr
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,240,'||chr(
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,240,'||chr(3
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,240,'||chr(39
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select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,240,'||chr(39))
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,240,'||chr(39)),
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,240,'||chr(39)),5
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,240,'||chr(39)),53
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,240,'||chr(39)),53,
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,240,'||chr(39)),53,l
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,240,'||chr(39)),53,le
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,240,'||chr(39)),53,lev
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,240,'||chr(39)),53,leve
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,240,'||chr(39)),53,level
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,240,'||chr(39)),53,level)
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,240,'||chr(39)),53,level)f
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,240,'||chr(39)),53,level)fr
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,240,'||chr(39)),53,level)fro
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,240,'||chr(39)),53,level)from
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,240,'||chr(39)),53,level)from
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,240,'||chr(39)),53,level)from d
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,240,'||chr(39)),53,level)from du
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,240,'||chr(39)),53,level)from dua
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,240,'||chr(39)),53,level)from dual
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,240,'||chr(39)),53,level)from dual
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,240,'||chr(39)),53,level)from dual c
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,240,'||chr(39)),53,level)from dual co
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,240,'||chr(39)),53,level)from dual con
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,240,'||chr(39)),53,level)from dual conn
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,240,'||chr(39)),53,level)from dual conne
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,240,'||chr(39)),53,level)from dual connec
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,240,'||chr(39)),53,level)from dual connect
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,240,'||chr(39)),53,level)from dual connect
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,240,'||chr(39)),53,level)from dual connect b
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by l
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by le
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by lev
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by leve
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<1
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<15
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155
select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;select substr(rpad(1,240,'||chr(39)),53,level)from dual connect by level<155;

154 rows selected.

Answer 4

Haskell, 100 98 bytes

^{-2 bytes thanks to Dennis}

main=mapM g[1..98];g n=putStrLn$take n$id<>show$"main=mapM g[1..98];g n=putStrLn$take n$id<>show$"

Try it online!

Surprisingly 2 4 bytes shorter than the obvious port of my Husk answer:

main=mapM putStrLn$scanl((.pure).(++))[]$id<>show$"main=mapM putStrLn$scanl((.pure).(++))[]$id<>show$"

Answer 5

JavaScript, 47 bytes

This can probably be improved.

Revisions

20 bytes have been saved so far between 3 versions!

Revision 5

There's been a lot of bytes saved with this revision:

• Don't assign a single-use variable for the quine to save 2 bytes
• Use templated strings for the quine to save a byte
• Use a single parameter (_) instead of no parameters (()) to save a byte

These three changes get it down to 47 bytes!!

(s=_=>{for(c of `(s=${s})()`)alert(name+=c)})()

Revision 4

On most pages, it seems that window.name is an empty string by default. We can take advantage of this to get 53 bytes!

(s=()=>{q="(s="+s+")()";for(c of q)alert(name+=c)})()

Unfortunately this is not the case for the snippet page, but try running it with the developer tools!

Revision 3

We can save 2 bytes, down to 55 bytes, by combining the two statements in the loop into one:

(s=()=>{q="(s="+s+")()",h="";for(c of q)alert(h+=c)})()

Revision 2

We can get down to 57 bytes by using an EcmaScript 2015 arrow function:

(s=()=>{q="(s="+s+")()",h="";for(c of q)h+=c,alert(h)})()

Revision 1

We can also get down to 61 bytes by using alert instead of console.log, if you consider that to be printing:

(function s(){q="("+s+")()",h="";for(c of q)h+=c,alert(h)})()

Initial Version

Initially, this script was at 67 bytes:

(function s(){q="("+s+")()",h="";for(c of q)h+=c,console.log(h)})()

Explanation

Here's the prettified code:

(function func() {
  quine = "(" + func + ")();";
  substr = "";
  for (char of quine) {
    substr += char;
    console.log(substr);
  }
})();

We start with a standard quine, then we define substr. We loop over each character of the quine, add it to substr, then output that.

Answer 6

Befunge-98 (PyFunge), 31 bytes

"2+,a<_@#-2$,k-'p11+1:g11+4+ff

Try it online!

Modification of a wrapping string literal quine that repeats printing prefixes until it prints everything.

Explanation:

"         Wrapping string literal that pushes the code backwards
 2+,      Add 2 to the space and print as "
   ,a<    Reverse direction and print a newline
"         Push the code again, but the right way this time
                          +4+ff   Push a quote
                       g11        Get the counter at (1,1)
                                  This is initially 32 (space)
                 p11+1:    Increment and store back at (1,1)
              -'          Subtract 31 from the counter
            ,k             Print counter many times plus one
          2$    Swap and check if the next number on the stack is 2
 2     _@#      If so, end the program as this is the leftover 2
   ,a           Print a newline and repeat

Answer 7

Jelly, 14 bytes

“Ṿ;¹¹ƤY”Ṿ;¹¹ƤY

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Answer 8

05AB1E, 17 bytes

0"D34çýη»"D34çýη»

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Answer 9

Python 2, 72 bytes

s,f="",'s,f="",%r\nfor i in f%%f:s+=i;print s'
for i in f%f:s+=i;print s

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Answer 10

Pyth, 17 bytes

j._jN*2]"j._jN*2]

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Answer 11

Japt -R, 11 bytes

CÇîQi"CÇîQi

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If the leading newline isn't acceptable, here's a 15 13-byte alternative:

Dõ_îQi"Dõ_îQi

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Answer 12

Pushy, 28 26 24 bytes

`I"Ov:L69w69`96w96L:vO"I

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Explanation:

`I"Ov:L69w79`                \ String literal: push this to stack
             96              \ Append backtick: I"Ov:L69w69`
               w             \ Mirror:          I"Ov:L69w69`96w96L:vO"I
                96           \ Append backtick: I"Ov:L69w69`96w96L:vO"I`
                             \ We now have the source code, backwards, on the main stack.

                  L:         \ len(stack) times do:
                    v        \     Move last character to auxiliary stack
                     O"I     \     Print the auxiliary stack

Answer 13

Java 10, 202 bytes

v->{var s="v->{var s=%c%s%1$c;s=s.format(s,34,s);for(int i=0;++i<s.length();)System.out.println(s.substring(0,i));}";s=s.format(s,34,s);for(int i=0;++i<s.length();)System.out.println(s.substring(0,i));}

Try it online.

Explanation:

quine part of the explanation:

• var s contains the unformatted source code.
• %s is used to input this String into itself with s.format(...).
• %c, %1$c, and the 34 are used to format the double quotes
• s.format(s,34,s) puts it all together

Challenge part of the explanation:

• for(int i=0;++i<s.length();) then loops i in the range [1, formatted_code_length)
• System.out.println(...) prints the String with trailing newlines
• s.substring(0,i) gets the substring of the formatted code in the character-range [0,i).