Vandevelo

Vandevelo is an input-only esolang by User:PythonshellDebugwindow.

Values

The only values in Vandevelo are nil and not nil.

Statements

Each line has zero or one statements.

Command	Meaning
var -> value	Set the variable var to value (lazy evaluation, evaluated again on each access)
var -!> value	Set the variable var to not value (e.g., (nil) if value == (not nil) else (not nil)) (lazy evaluation, evaluated again on each access)
var ~> value	Set the variable var to value (strict evaluation, evaluated immediately)
var ~!> value	Set the variable var to not value (e.g., (nil) if value == (not nil) else (not nil)) (strict evaluation, evaluated immediately)
x :: y	JavaScript (x) && (y); (e.g., short-circuit if; nil is falsy and not nil is truthy)

Expressions

Usable within statements.

Expression	Result
var?	The variable var (error if undefined)
x == y	Not nil if x == y else nil
x != y	Nil if x == y else not nil

Comments

Comments last until end-of-line, and are denoted by --, e.g. 2? -> 2? --Infinite loop.

Conventions

Variable names have to match the regex [A-Za-z0-9_&*$]+, but conventions are to number them starting with 0 incrementing by 1.

Special variables

Nil contains nil, and Inp returns user input when accessed (nil if input in {ε, 0, space} else not nil).

Truth-machine

0 -!> Nil?
1 -> Inp? == 0?
2 -> 2?
1? :: 2?