// Not entirely unlike ST-72...

realObjects = {}
realObjectFor = function(x) {
  if (x instanceof Object)
    return x
  else {
    if (realObjects[x] == undefined)
      realObjects[x] = new Object(x)
    return realObjects[x]
  }
}

Boolean.prototype.st72Behavior = function() { return "Boolean" }
Number.prototype.st72Behavior = function() { return "Number" }
String.prototype.st72Behavior = function() { return "String" }

ometa ST72 {
  exactly :x = :y ?(x == y) -> x,
  realObject = :x -> realObjectFor(x),
  step       = realObject:recv apply(recv.st72Behavior(), recv),
  eval       = step* anything,
             
  answer     = empty,

  Number :Self  = '+' eval:x answer(Self + x)
                | '-' eval:x answer(Self - x)
                | '*' eval:x answer(Self * x)
                | '/' eval:x answer(Self / x)
                | '=' eval:x answer(Self == x)
                | '<' eval:x answer(Self < x)
                | '>' eval:x answer(Self > x),

  String  '('   = eval:x ')' answer(x)
}

messageStream = ["(", 2, "*", 3, ")", "+", 4]
ST72.matchAll(messageStream, "eval")