Zfuck
Zfuck is a minimal Turing-complete 3-command variation of Smallfuck discovered by User:PythonshellDebugwindow. It was developed independently of Nanofuck.
Memory
Like Smallfuck, Zfuck operates on a tape of bits, but unlike Smallfuck, Zfuck uses a left- and right-unbounded tape. The tape is initialized with the program's input as a binary number left- and right-padded with zeros, and the program's output is all previously and currently visited cells in the tape at the end of the program (if it halts) as a binary number.
The minimization process
We start out with Smallfuck's 5 commands.
><*[]
We can combine *> into } to get 4 commands.
}<[]
We can also define the empty loop [] to be a nop and merge ]< into ) to get 3 commands.
}[)
Simple translation to and from SmallfuckU
This version of Smallfuck has an unbounded tape. Let's call it SmallfuckU for the sake of brevity.
| Zfuck | SmallfuckU |
|---|---|
} |
*>
|
[ |
[
|
) |
]<
|
| SmallfuckU | Zfuck |
|---|---|
> |
}[)}
|
< |
[)
|
* |
}[)
|
[ |
[
|
] |
)}[)}
|
Examples
Infinite loop
[}[))}[)}}[)[}[)}[))
Truth-machine
[}[)}[))
Interpreter in JavaScript
The first argument is the code and the second is the initial tape. Undefined behaviour for a negative cell pointer. Also severely golfed and memory-inefficient as a result.
var zfuck=(c,m)=>eval("var p=0;"+c.replace(/}/g,"m+=~0];m~p]=!m~p++];").replace(/\)/g,"}p--;").replace(/\[/g,"while(m[p]){").replace(/~/g,"[").replace(/{}/g,"break;"));