1. Programming your way
back to where you were
Riviera.rb
5 March 2013
Jean-Baptiste Mazon
@jbmazon

2. Introduction
● What
● Cheats
● Hacks
● Language features

3. A quine is a computer
program which takes no
input and produces a copy
of its own source code as
its only output.
The standard terms for
these programs in the
computability theory and
computer science literature
are self-replicating
programs, self-reproducing
programs, and
self-copying programs.

4. Well-known pattern
D
R
Y

5. Well-known pattern
Do
Repeat
Yourself

6. IOCCC 1994: smr

7. IOCCC 1994: smr
(categorized: Worst Abuse of the Rules)

8. The recursive aproach
(live demo)

9. ASCII quine
(live demo)

10. Generic quine
(but it's still ASCII-based)
(live demo)

11. A brief math digression
● Fixed-point theorem
● Cool functions to fix
– print source
– interpret
– compile
– gzip source

12. Quines

13. Quines

14. Quines

15. Quine

16. Quine
● “Yields falsehood when
preceded by its quotation”
yields falsehood when
preceded by its quotation.

17. Quine
● “Yields falsehood when
preceded by its quotation”
yields falsehood when
preceded by its quotation.
● quine “hello”.
→ hello “hello”.

18. Terminology
● code
● data
● intron

19. Bootstrapping

20. Multiquines

21. Examples

22. Examples
● (λx.xx) (λx.xx)

23. Examples
● (λx.xx) (λx.xx)
● #!/bin/sh
cat $0

24. Examples
● (λx.xx) (λx.xx)
● #!/bin/sh
cat $0
● #!/bin/cat

25. Examples
● (λx.xx) (λx.xx)
● #!/bin/sh
cat $0
● #!/bin/cat
● puts(s = <<e, s, 'e')
puts(s = <<e, s, 'e')
e

26. Examples
● (λx.xx) (λx.xx)
● #!/bin/sh
cat $0
● #!/bin/cat
● puts(s = <<e, s, 'e')
puts(s = <<e, s, 'e')
e
● Q

27. Other examples

28. Final thoughts
● incompleteness
● trusting trust
● Quine Central
● backup
● introspection
● anything else?

29. References
● Wikipedia
● David Madore's quine page
● C2
● Russ Cox's “Zip Files All The Way Down”
● Dan Piponi's “Quine Central”