\ Stack--pushdown data structure built on top of a List              vandys
only extensions definitions

List -> subclass: Stack

Stack -> :method push ( elem self -- )   -> add method;
Stack -> :method peek ( self -- elem )   dup List>nelem @
   dup 0= abort" empty"   1- cells swap List>elems @ + @ method;
Stack -> :method pop ( self -- elem )   dup -> peek
   swap List>nelem dec method;
Stack -> :method do ( arg 'fn self -- )   super-> reverseDo method;

Stack -> :method reverseDo ( arg 'fn self -- )   super-> do method;