"cons" -> joy_cons stack expression
"dup" -> joy_dup stack expression
"first" -> joy_first stack expression
+ "pop" -> joy_pop stack expression
"rest" -> joy_rest stack expression
_ -> Err ("Unknown word: " ++ symbol)
Err msg -> Err msg
+joy_pop : JList -> JList -> Result String (JList, JList)
+joy_pop stack expression =
+ case pop_any(stack) of
+ Ok (_, s0) -> Ok (s0, expression)
+ Err msg -> Err msg
+
+
joy_rest : JList -> JList -> Result String (JList, JList)
joy_rest stack expression =
case pop_list(stack) of