finally, the expressions -- remember the defaults


  
  bexpr   : '(' ')'                {  $$ = mkterm("()"); }
          | '(' term ')'            { $$ = $2; }
          | '{' '}'                  { $$ = mkterm("{}");; } 
          | '{' term '}'            { $$ = mkterm("{}",$2); }
          | '(' term COMM clist ')' { $$ = mkterm(strof($3),$2,$4); }
          | '(' term '.' term ')'    { $$ = mkterm("#dot:",$2,$4); }
          ;
  
  expr : bexpr | lexpr | sexpr | EXPR { /* from defaults */} ;
  
  

slide: finally, the expressions -- remember the defaults