Hi all,
thanks a lot for your help in this travel through OCaML but I have still
a question. I have tried to write a polymorphic stack code attached but
I don't understand its behavior:

    # open Stack;;
    # let s = empty;;
    val s : '_a Stack.stack = {c = []}
    # push s 7;;
    - : unit = ()
    # push s 25;;
    - : unit = ()
    # let s1 = empty;;
    val s1 : int Stack.stack = {c = [25; 7]}
    # push s1 "Hello";;
    Error: This expression has type string but an expression was expected of type
              int

Apparently seems that I can have only a variable of type stack and any
other call to its constructor links the new variable to the old one. 
This means that once I have put an int inside I can't have a second
stack for characters or what else? This behavior is completely
unexpected and I can't explain it.

I'm sure I'm doing something wrong but I can't say what it is. Do you
have any idea about?

TIA
Walter

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