Fuck Your brain for a great good
by Ankit Shukla
Esoteric programming language
"An esoteric programming language is a computer programming language designed
to experiment with weird ideas, to be hard to program in, or as a joke, rather than for practical use."
Today's Menu
- Turing-completeness
- Brainfuck
- Piet
- Fractran
Turing machine
Can solve all possible algorithmic computations
-
Infinite ribbon of (finite state) cells
-
Left / right movement
-
Choice and action on current cell
Turing complete languages
" A given programming language is said to be
Turing - complete if it can be shown that it is computationally equivalent to a Turing machine."
Brainfuck
♥
Invented in 1993 by Urban Müller
♥ Goal : Turing-Complete language which needs a minimal compiler only.
♥
Müller's Amiga
compiler
was 240
bytes in size
It consists of 8 operators
Basics
✈ The idea behind Brainfuck is memory manipulation.
✈
You are given an array
of 30,000 1byte memory blocks
✈
A Brainfuck program has an implicit byte pointer,
called "the pointer"
initially all set to zero.
✈ Within this array, you can increase the memory
pointer, increase the value at the memory pointer, etc.
Operators
>
becomes ++p;
<
becomes --p;
+ becomes ++*p;
- becomes --*p;
.
becomes putchar(*p);
, becomes *p = getchar();
[ becomes while (*p) {
]
becomes
}
ツ
Test loop ⇒ [ ]
ツ
Byte IO ⇒ , .
♛ Rules ♛
® Characters besides the 8 operators should be considered comments.
® All memory blocks on the "array" are set to zero at the beginning of the program.
® And the memory pointer starts out on the very left most memory block.
® Loops may be nested as many times as you want.
But all [ must have a corresponding ].
Examples
[-]
Enter a loop that decreases the value stored at the current memory pointer
until it reaches zero, then exits the loop.
+++++[-]
C ➳ *p=+5;
while(*p != 0)
{
*p--;
}
Incrementing the current memory ptr value to 5, then entering a loop that dec
the value located at the memory ptr till it is zero, then exits the loop.
More examples
[.,] Echo ☂ EOF returns 0
>>>++
This will move the memory pointer to the fourth memory block, and increment the
value stored there by 2.
memory blocks
-------------
[0][0][0][2][0][0]...
^
memory pointer
>>>>++<<+>>+
memory blocks
-------------
[0][1][0][3][0][0]...
^
memory pointer
Hello World
+++++ +++ Set Cell #0 to 8[ >++++ Add 4 to Cell #1; this will always set Cell#1 to 4 [ as the cell will be cleared by the loop >++ Add 4*2 to Cell #2 >+++ Add 4*3 to Cell #3 >+++ Add 4*3 to Cell #4 >+ Add 4 to Cell #5 <<<<- Decrement the loop counter in Cell #1 ] Loop till Cell #1 is zero >+ Add 1 to Cell #2 >+ Add 1 to Cell #3 >- Subtract 1 from Cell #4 >>+ Add 1 to Cell #6 [<] Move back to the first zero cell you find; this will be Cell #1 which was cleared by the previous loop <- Decrement the loop Counter in Cell #0] Loop till Cell #0 is zero
hELLO wORLD
The result of this is:
Cell No : 0 1 2 3 4 5 6Contents: 0 0 72 104 88 32 8Pointer : ^
>>. Cell #2 has value 72 which is 'H'>---. Subtract 3 from Cell #3 to get 101 which is 'e'+++++ ++..+++. Likewise for 'llo' from Cell #3>>. Cell #5 is 32 for the space<-. Subtract 1 from Cell #4 for 87 to give a 'W'<. Cell #3 was set to 'o' from the end of 'Hello'+++.----- -.----- ---. Cell #3 for 'rl' and 'd'>>+. Add 1 to Cell #5 gives us an exclamation point>++. And finally a newline from Cell #6