Quine

Play with Quines.

Inspiration from Quine Relay, and especially from this comment.

Level1

Basic quine where processing (compiling, running..) input file a gives output file b, where hash(a)==hash(b), because b has the exact same contents as a.

Eg: for a compiled language like C, it goes like this:

$ cc a.c -o a_c && ./a_c > b.c && diff a.c b.c && echo "QUINE!!" || echo "You lose"

Note: for interpreted languages like Python, there is no compilation phase, obviously:

$ python a.py > b.py && diff a.py b.py && echo "QUINE!!" || echo "You lose"

Level2

Indirect quine where processing input file a in language A gives output file b in another language (or form) that must be processed again by another tool, to obtain the original file a. Can be scaled to more than one intermediate languages, before getting back to a.

Eg: Start from a C file that when compiled/run produces a Python file, which when run produces the initial C file again:

$ cc a.c -o a_c && ./a_c | python > b.c && diff a.c b.c && echo "QUINE!!" || echo "You lose"

But that naive C<=>PY example is "cheating", eg: unrolling the loop once, and hence is not scalable beyond two languages.

A smarter example is the PL<=>PY example, that separate the two language loops, and thus can be scaled to more than two.

Level2+

Add a 3rd language in the loop of Level2, this time with language : V, C and Python.

Start with V which produces a C, which produces a Python, which produce V back again. V => C => PY => V..

Already done:

• Perl/Python (2 lang)
• V/C/Python (3 lang)
• Nelua/Python/V/C (4 lang)

Idea: make another quine-relay using only languages not already used by mame. Eg: Nelua, V, Odin, Zig, VHDL, WAT, RPL, ..

Level3 : hybrid contents ? (non-quine)

Try to split parallel ways to process a single file to different outputs

Eg: Start from a c,c++,etc.. hybrid source file A (which means a single file contains multiple languages), compile it separately as C and C++ and run both : former produces a eg: shell script, the latter eg: a Python script:

A -+-C++-> B=SH
   \--C--> C=PY

Level4 : Frankenquine ? Quinea pig ? Superquine ? Quinception ?

Try to split parallel ways from a single file, but converging back to the same source, eventually.

Eg: Start from a c/++ hybrid source file A (which means a single file contains multiple languages), compile it separately as C and C++ and run both : former produces a shell script, the latter a Python script:

A -+-C++-> B=SH --+-> A
   \--C--> C=PY --/