elon-deadfish

$ Deadfish interpreter $
{
  "cmd" define
  cmd "i" equal { x 1 add "x" define } do
  cmd "d" equal { x 1 subtract "x" define } do
  cmd "s" equal { x x multiply "x" define } do
  cmd "o" equal dup
  { x print } do { "\n" print } do-not
  "cmd" undefine
} "parse" define

0 "x" define
set
  "\n>>" print
  "String" input
  untie
  length 0 not-equal { set
    shift parse
    x 256 equal x -1 equal or
    { 0 "x" define } do
    length 0 not-equal { repeat } do
    pop
  forget } do
repeat