/* (Definitions Section) */
%start program
%token LET INTEGER IN
%token SKIP IF THEN ELSE END WHILE DO READ WRITE
%token NUMBER
%token IDENTIFIER
%left ’-’ ’+’
%left ’*’ ’/’
%right ’ˆ ’

%%
 /* (Rules Section) */
program : LET declarations IN commands END ;
declarations : /* empty */
	| INTEGER id seq IDENTIFIER ’.’
;
id seq : /* empty */
	| id seq IDENTIFIER ’,’
;
commands : /* empty */
	| commands command ’;’
;
command : SKIP
	| READ IDENTIFIER
	| WRITE exp
	| IDENTIFIER ASSGNOP exp
	| IF exp THEN commands ELSE commands FI
	| WHILE exp DO
;
exp : NUMBER
	| IDENTIFIER
	| exp ’<’ exp
	| exp ’=’ exp
	| exp ’>’ exp
	| exp ’+’ exp
	| exp ’−’ exp
	| exp ’∗’ exp
	| exp ’/’ exp
	| exp ’ˆ ’ exp
	| ’(’ exp ’)’
;
%%
 /* (C Section) */
main( int argc, char *argv[] )
{ extern FILE *yyin;
	++argv; −−argc;
	yyin = fopen( argv[0], ”r” );
	yydebug = 1;
	errors = 0;
	yyparse ();
}
yyerror (char *s) /* Called by yyparse on error */
{
	printf (”%s\n”, s);
}