Hello today I am a unicorn

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Hello today I am a unicorn
Paradigm(s) Imperative
Designed by Hakerh400
Appeared in 2020
Computational class Turing complete
Major implementations Interpreter
File extension(s) .txt


Hello today I am a unicorn is a Turing-complete programming language that has only two variables.

Overview

There are only two variables: x and y. Both are non-negative integers of unlimited size.

Source code consists of zero or more instructions. Any instruction can be prefixed by a label.

Each instruction begins with the variable name it uses (x or y), then operator that is applied and operands.

Operator Xor

Denoted by ~. No operands. Inverts the lowest bit of the variable. Example:

x~

Value of x before: 123
Value of x after: 122

Operator Shift left

Denoted by +. No operands. Performs binary shift to the left. Example:

y+

Value of y before: 5
Value of y after: 10

Operator Shift right

Denoted by -. No operands. Performs binary shift to the right. Example:

x-

Value of x before: 15
Value of x after: 7

Operator If

Denoted by ?. Two operands (and they are labels). If the lowest bit is 1 jump to the first label, otherwise jump to the second label. Example:

y? label1 label2
label1: x+
label2: x-

If y is odd, x will be shifted left and then shifted right. If y is even, x will only be shifted right.

Note: all instructions except this simply increment instruction pointer.

I/O format

Input is a non-negative number. It is written in the x variable before program starts, while y is initially 0. When program terminates, y contains the output.

Examples

Cat

Note: assuming the same I/O format as described here for converting from/to ASCII strings.

      x? copy exit
copy: x- y+ y~ y+
      x? flip next
flip: y~
next: x- x? copy exit
exit: x~

Computational class

The variables x and y effectively implement two stacks of bits; you can push to these via a left-shift (possibly followed by an xor), pop them via a right-shift, and test the bottom bit via the if operator. Because the language also allows arbitrary control flow, this allows two-stack machines to be implemented more or less directly (a two-counter machine can also be implemented via treating the counter as a stack of multiple 0 bits above a single 1 bit), making the language Turing complete.

Interpreters

Interpreter