syntax (switch (EXPR) CODE) { # eval the expr first to avoid
                                  # reevaluation at each case
      my $var = new_unique_symbol;
      code {
        {
          $var = EXPR;
          switch_aux($var) CODE  
        }
      }
    }
    syntax (switch_aux (EXPR) { case CODE_t { CODE_c } CODE_e }) {
      # else is left as an excercise.
      code{
        if(case(EXPR,CODE_t)){
          CODE_c
        } else {
          switch_aux(EXPR){ CODE_e } # notice the recursion here
        }
      }
    }
    syntax (case (EXPR,INTEGER)){
      code {
        (EXPR == INTEGER)
      }
    }
    syntax (case (EXPR,STRING)){
      code {
        (EXPR eq STRING)
      }
    }
    syntax (case (EXPR,LIST)){
      code {
        (grep EXPR, LIST)
      }
    }
    syntax (case (EXPR,REGEX)){
      code {
        (EXPR =~ REGEX )
      }
    }
    syntax (case (EXPR,HASH)){
      code {
        (exists EXPR, HASH)
      }
    }
    syntax (case (EXPR,SUB)){
      code {
        SUB(EXPR)
      }
    }