Generic Packages

["Eyal Ben-gal" <eyalbengal@hotmail.com>]

I have two packages for implementing a polynom.
In the first package I'm using linked list (PolyList) and the second is an
array (Fixed_Polynom)
both of the packeges supporting the same package interface such as:
"+", "-", SetFirst, SetNext, GetElement,

I've tried to create a generic package which will implement
"*", drivation calculation, print and so on.  (lets call this packes
general_pol) which ofcourse using the SetFirst, SetNext functions

when I'm using general_pol with the decleration of explicit type which will
be the type to use from the abstruct types of the erlier packages there is
no problem,

but when i'm trying to make it generic I fail since I'm calling the abstruct
data type functions and the compiler ofcourse can't know how to connect that
to the type I'm using for the SetFirst, SetNext functions.

How can I do that ?
generic

type Polynom is private

package general_Pol is

function sum (frst :Polynom; scnd :Polynom) return Polynom;

function "*" (first:Polynom; second:Polynom) return Polynom;

function derive (plnm:Polynom) return Polynom;

procedure print (plnm:in out Polynom);

function "=" (first:Polynom; second:Polynom) return boolean;

function SetPolynom return Polynom;

function Count (x:Polynom) return integer;

end general_Pol;



How can I create it Generic that will implement in first instatiation for
PolyList the additional operations,

and later the same for Fixed_Polynom.

Thanks,

        Eyal.