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Paradigm(s) Imperative
Designed by User:ZippyMagician
Appeared in 2021
Memory system Cell-based
Computational class Turing-complete
Reference implementation Unimplemented
File extension(s) .cpy

cpy (from memcpy) is a Turing tarpit designed by User:ZippyMagician.


cpy is composed of instructions, separated by lines. These instructions come in the form

X <op> Y

, where X and Y are numbers and op is one of the following:

Op Description
-> Move [X] into [Y] and decrement if X > Y, else increment
<-> Copy [X] into [Y]
<- Jump to line X if [Y] > 0

Memory cells 0 and 1 are reserved. Writing a value to 0 will output the value and then clear that address, and moving from one will give a byte of STDIN (whether this is the ASCII code or a number is implementation defined). If this cell is cleared via a mov operation, it will be replaced with the next byte or a 0-byte if there is no more input. Memory is in the form of unsigned 8-bit numbers, initialized to 0. The maximum size of memory is undefined, but recommend to be at least 216 cells. All characters besides numbers and operators are ignored


Cat program


Computational Class

cpy can be proven Turing complete by translation of Szewczyk notation for Minsky machine, which is a proposed notation for a minimalistic Minsky Machine syntax, such as the following program

1 -1
1 1
1 1

Translation can be accomplished as follows:

3 <- 3

for each X -1

X+4 -> X+4

for each X Y (# = line# 0-indexed)

#+2 <- X+4
Y+offset+1 <- 3

where offset must be calculated at translation time, such that it jumps to the start of the Yth command (which may or may not be the Yth line + 1, depending on whether the X Y command was used or not). Once finished, a transpiler written in Rust can be found Here.


  • Common Lisp implementation of the cpy programming language.