\ case 97.8.27 (from dpANS docs)

0 constant case  immediate

: of
  1+ >r  postpone over  postpone =
  postpone if  postpone drop  r> ;
immediate

: endof
  >r  postpone else  r> ; immediate

: endcase
  postpone drop
  ?dup if
    0 do  postpone then  loop
  then ; immediate