Super Stack!
Super Stack! is a stackbased esoteric programming language by User:Orange.
How programs are run
Programs consist of keywords separated by spaces, tabs, and/or newlines. There is only one stack the program can manipulate.
Instructions
Instruction  Description 

123

Push a number onto the stack. 
add

Pop two numbers, add them, and push the result. 
sub

Pop two numbers, subtract the first from the second, and push the result. 
mul

Pop two numbers, multiply them, and push the result. 
div

Pop two numbers, divide the first from the second, and push the result. 
mod

Pop two numbers, perform modulus on the first and second, and push the result. 
random

Pop the top number, and push a random number from 0 to the number popped minus 1. So if you have the number 5 and you use random, you will get 0, 1, 2, 3, or 4. 
and

Pop two numbers, and them, and push the result. 
or

Pop two numbers, or them, and push the result. 
xor

Pop two numbers, xor them, and push the result. 
nand

Pop two numbers, nand them, and push the result. 
not

Pop the top number, not it, and push the result. 
Note:
 
output

Pop the top number and output it as a number followed by a space. 
input

Get a single number from input and push it. 
outputascii

Pop the top number and output as an ascii character. 
inputascii

Get a string of characters from input and push each ascii character on the stack backwards, so the first letter in the string is on the top, and the last letter of the string is on the bottom. 
pop

Pop the top number and discard it. 
swap

Swap the top two numbers. 
cycle

Put the top number on the bottom of the stack. 
rcycle

Put the bottom number on the top of the stack. 
dup

Duplicate the top number. 
rev

Reverse the entire stack. 
if

While loop. If the top number is true, loop. Does not pop top number. 
fi

End loop. 
quit

End program. 
debug

Output entire stack. (Does not pop anything.) 
Example Programs
Hello, World!
0 33 100 108 114 111 87 32 44 111 108 108 101 72 if outputascii fi
First, push ASCII codes onto the stack for "Hello, World!" Then while there are nonzero numbers on the stack output them.
Cat program
1 if 0 inputascii if outputascii fi `outputstack pop 10 outputascii fi
Explanation:
 1 is pushed and then a while loop is entered. The 1 makes the loop run forever.
 0 is pushed so we can tell when input ends.
 Input is pushed onto the stack.
 While the top number is not 0, pop and output number.
 Pop the 0.
 Push 10 and output it(new line).
 The stack now only has the number 1 on it, so the program will loop again.
As you can see keywords can be separated by spaces or newlines.
Fibonacci sequence
0 1 if dup output dup cycle add fi
 Push 0 and 1 on the stack to start the fib.
 If for an infinite loop.
 Output the top of stack.
 Dup top number then put it on the back of the stack.
 Add the top two.
 Loop. Top of the stack will always be more than 0.
Guess the pass code
0 58 101 100 111 67 32 115 115 97 80 32 114 101 116 110 69 if outputascii fi pop inputascii `compare each letter 109 sub not if pop 97 sub not if pop 114 sub not if pop 115 sub not if pop 104 sub not if pop 0 100 101 116 110 97 114 71 32 115 115 101 99 99 65 if outputascii fi pop quit fi fi fi fi fi `wrong 0 71 78 79 82 87 if outputascii fi pop
A little game. Guess what the password is.
FizzBuzz
The stupid fizzbuzz problem.
100 if dup 101 add dup output dup 3 mod not if pop 0 122 122 105 102 `fizz if outputascii fi pop 0 fi pop dup 5 mod not if pop 0 122 122 117 98 `buzz if outputascii fi pop 0 fi pop 10 outputascii `newline pop 1 add fi inputascii
Simple chat bot
1 if pop 0 58 116 117 112 110 105 if outputascii fi pop inputascii 0 5 random if pop cycle if cycle fi 0 fi pop 0 58 116 117 112 116 117 111 if outputascii fi pop cycle if dup outputascii cycle fi 10 outputascii 1 fi
First the program gets a string inputted onto the stack. Strings are represented by a 0 and then a series of characters that lead up to the next string. After the input, we randomly cycle from string to string. Then, we output the string and loop the program.
Implementations
 v2 of the Python implementation
 Super Stack!/superstack.ml, an implementation in Ocaml that almost matches the specs
 Super Stack! compiler for the Digirule, as part of the dgtools package. Try it online here.
Computational Class
Super Stack! is Turingcomplete. Its only data structure is actually more "powerful" than a simple stack, due to commands instructions like cycle
and rcycle
. It is easy to transpose any given brainfuck into an equivalent Super Stack! program, for instance using the following algorithm:
 Begin the program with the code
1 0
.  Replace every brainfuck instruction by the matching Super Stack! instruction sequence in the conversion table below:
brainfuck  Super Stack! 

> 
cycle dup 1 add not if 0 swap not fi pop

< 
rcycle dup 1 add not if not swap cycle dup fi pop

+ 
254 sub if 255 add fi

 
dup not if swap 255 add swap not fi pop 1 sub

. 
dup outputascii

, 
pop inputascii

[ 
if

] 
fi

Note that this conversion is far from being efficient; its only purpose is to prove that Super Stack! is brainfuckequivalent. It emulates an infinite tape, navigating with cycle
and rcycle
, pushing an extra 0 every time 1 is on top. It is assumed that the tape is right and leftinfinite and that brainfuck cells contain numbers between 0 and 255, with wrapping for +
and 
. It is also assumed that inputascii
reads one character only, which may be slightly inconsistent with the specifications above.