Symmetry

Symmetry is an esoteric programming language designed under the observation that most traditional languages use Hashmaps to store data, but that this practice is more for programmer's convenience than for necessity (see: any other esolang ever, where the data model is anything but a hashmap).

Idea

Most traditional languages use hashmaps to store data; that is, a key→value pair. Symmetry, on the other hand, uses a Wikipedia:Bidirectional map, or hashbag, to store its data; that is, key↔key pairs. This means, essentially, that bm[k]=v↔bm[v]=k (the arrow there being "iff" in this case, not the earlier-used key↔key syntax). This leads to a few interesting properties; for example, that the assignment expression x=y is logically equivalent to y=x.

Syntax

The syntax of Symmetry is fairly trivial; it looks quite like a normal language (as one of the common reasons esolangs look abnormal is that they're dealing with a strange data model, which we are not here). Note that all syntax is tentative; none of it will necessarily stay for long, until the author feels it is complete.

Tokenization

Regex	Tag	Feature name
^[\s]+	NULL	Whitespace is ignored.
^"[^"\\]*(?:\\.[^"\\]*)*"	STR	Strings are enclosed in double quotes, but may have double quotes inside them backslash-escaped
^[0-9]+(\.[0-9]+)?	NUM	Numbers are both floating-point and integers; they are of the most traditional of syntaxes
^=	ASSGN	Assignment: One of the must integral parts of languages, especially symmetry
^(\+|\*|-|/|%|&|\||^|<=|>=|<|>|==)	OP	Operators are useful. Arithmetic (including modulus), boolean, relational.
^[{}()[\]]	BRACK	Curly brackets close of blocks, parentheses group expressions, and square brackets are reserved in case I ever feel like using them
^[a-zA-Z_][a-zA-Z0-9_]*	NAME	Identifiers. Really just used for functions; can't be used in assignment.
^,	NAME
^IF	IF	Conditionals
^ELSE	ELSE	Failure conditionals
^WHILE	WHILE	Loop-de-loop

Grammar

value  ::= STR | NUM ;
pexp   ::= "(" exp ")" ;
fexp   ::= NAME "(" [{exp ","} exp] ")"
exp    ::= fexp | pexp | value OP value ;

ifthen ::= "IF" exp "{" {stmt} "}" {"ELSE" ifthen} ["ELSE" "{" {stmt} "}"] ;
while  ::= "WHILE" Exp "{" {stmt} "}" ;
stmt = while | ifthen | exp