()s

The title of this article is not correct because of technical limitations. The correct title is actually {}s.

{}s (pronounced: Sets) is an esolang made by User:AmNow.

Commands

{}: Expression (can be nested) ie: {%+%}
%: the constant 2.
(ANY NUMBER): A variable.
<: Assignment. ie: 2<{%/%}
Note: The value before the < operator must be a number, not a billion %s, strung with math. (Don’t worry, it will not represent the value in it.)
[x, {...}]: Loop, While x isn’t 0, do the expression.
+,-,*,/ are math operators, referring to plus, minus, multiply, and divide respectively. {}s follows PEMDAS order.
=: Equal To
\: NOT Equal to
~: Less Than
$: Greater Than
&: Logical AND
@: Logical OR
|: Logical XOR
!: Logical NOT
#: switches from Unicode character output to Number output and vice versa. (starts on Unicode)

A write to 0 will print the value assigned to it (like 0 in `) and a reference to 1 will get from the input.

EOF is 0.

Programs

Truth Machine

# 2<1 0<2 [2, {0<2}]

Cat Program

This example implements a repeating cat program which terminates on a null character input:

2<1 [2, {0<2 2<1}]

Looping Counter

This program queries the user for an integer number, counts up from one (1) to the same, and displays during each cycle on a line of its own a catena of asterisks (“*”) tantamount to the current counter state:

#
2 < 1
3 < {% / %}
4 < {% - %}
5 < {{% * % * % * % * %} + {% * % * %} + %}
6 < {{% + %  + {% / %}} * %}
#
[2 $ {% - %},
  {4 < {% - %}
    [4 ~ 3, {0 < 5 4 < 4 + {% / %}}]
    0 < 6 
    2 < 2 - {% / %}
    3 < 3 + {% / %}}]

Computational class

{}s is Turing-complete, which can be proven via translation from Portable Minsky Machine Notation.

PMMN	{}s
inc(X);	X < {2 + {% / %}}
dec(X);	C < X [C, { X < {X - {% / %}} C < {% - %} }]
while(dec(X)) { ... }	[X, { X < {X - {% / %}} ... }]
if(dec(X)) { ... }	C < X L < X [C, { X < {X - {% / %}} C < {% - %} ... }]
else { ... }	L < {L = {% - %}} [L, { L < {% - %} ... }]

Every C and L in the translated program must be replaced by a variable unused by a register in the PMMN program. Every C can be replaced by either the same variable or by different variables. Every L must be replaced by the same variable in the same scope, and a different variable in a different scope (so every scope will have a unique L variable).

Due to how I/O works, variables 0 and 1 cannot be used. These variables must be replaced by unused variables if they are in the translated program.

Interpreter

• Common Lisp implementation of the {}s programming language.