program         -> statement* EOF ;

statement       -> exprStmt | printStmt | declaration | block ;

exprStmt        -> expression ";" ;
printStmt       -> "print" expression ";" ;
declaration     -> "var" IDENTIFIER ( "=" expression )? ";" ;
block           -> "{" statement* "}" ;

expression		-> assignment

assignment      -> IDENTIFIER "=" assignment | equality ;
equality		-> comparison ( ( "==" | "!=" ) comparison )* ;
comparison		-> term ( ">" | ">=" | "<" | "<=" term )* ;
term			-> factor ( ( "+" | "-" ) factor )*
factor			-> unary ( ( "*" | "/" ) unary )* ;
unary			-> ( "!" | "-" ) unary | primary ;
primary			-> "(" expression ")" | IDENTIFIER | NUMBER | STRING | "true" | "false" | "nil" ;