%{
    /* C definitions */ 
void yyerror(char*);

#define YY_SKIP_YYWRAP
#define YYSTYPE double
int yywrap(void) { return 1; }
#include "myparser.h" /* cf. bison's -o option */
%}
    /* definitions */
%option yylineno
%option always-interactive
%%
    /* rules */  
[ \t]+          { /* do nothing */ }
[0-9]+(\.[0-9]+)?(E[+\-]?[0-9]+)?   { 
   sscanf(yytext, "%lf", &yylval); return NUMBER; 
                }
[+\-*/()\n]     { return yytext[0]; }
"*+"            { return FOO; }
.               {
   yyerror("Illegal character."); return '\n'; 
} 
%%
    /* additional C code */