grammar.txt

expr         : KEYWORD:var IDENTIFIER EQ expr
             : comp-expr ((KEYWORD:and|KEYWORD:or) comp-expr)*

comp-expr    : NOT comp-expr
             : arith-expr ((EE|LT|GT|LTE|GTE) arith-expr)*

arith-expr   : term ((PLUS|MINUS) term)*

term         : factor ((MUL|DIV) factor)*

factor       : (PLUS|MINUS) factor
             : power

power        : call (POW factor)*

call         : atom (LPAREN (expr (COMMA expr)*)? RPAREN)?

atom         : INT|FLOAT|STRING|IDENTIFIER
             : LPAREN expr RPAREN
             : if-expr
             : func-def

if-expr      : KEYWORD:if expr KEYWORD:then expr
               (KEYWORD:elif expr KEYWORD:then expr)*
               (KEYWORD:else expr)?

for-expr     : KEYWORD:for IDENTIFIER EQ expr KEYWORD:to expr
               (KEYWORD:step expr)? KEYWORD:then expr

while-expr   : KEYWORD:while expr KEYWORD:then expr

func-def     : KEYWORD:func IDENTIFIER?
               LPAREN (IDENTIFIER (COMMA IDENTIFIER)*)? RPAREN
               ARROW expr