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”